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Pond, James Pond
January 9, 2014, 06:25 AM
I ask this with mainly longer range shooting in mind.

I am not yet at a level where BC makes much difference, but as I develop loads I am trying to select the bullet-powder combinations now that will meet these needs later.

If I have a good long range load, even if I only use it to shoot 100-300m now, every shot will serve to make me more used to its performance and characteristics.

So that means making smart bullet choices now.

As some know I have been developing a load for my 155gr Amax.

However, as I understand it, longer range shooting would mean somewhat heavier bullets. So I am looking at 167-180gr bullets.

I also understand that Ballistic Coefficient will affect how well the bullet works further away. But how big a deal is it?

My Amax bullets are listed as .435 BC.
By contrast I can get a Hornady 168gr HPBT with a BC of .450 or a 180gr SST with a BC of .480.
Then there is the Lapua offering: the 167gr and 180gr Scenars at .446 and .482 BC respectively and then the impressive .498 of the 170gr Lockbase bullet! :eek:

So the Lockbase is most attractive: an impressive BC in .30 cal, and a lower weight meaning a smidge less recoil.

Here is the issue: comparing the Lockbase with the 180gr SST the Lapua is €10 per 100 more expensive. That adds up.

I know this is mostly down to me, but I want to put the BC difference in perspective. If the BC difference will make next to no discernible change in performance, it makes the choice easier. If it means a noticeable improvement in consistency/accuracy and a flatter flight that also carries a lot of value to me.

So, is the lower weight and .018 greater BC worth an extra €100 per 1000 rounds?

MtnCreek
January 9, 2014, 10:11 AM
If I have a good long range load, even if I only use it to shoot 100-300m now, every shot will serve to make me more used to its performance and characteristics.

At 300 meters, you're not going to see much of a difference between a 155 amx and a 175smk / 178 amax (bullets I have exp with), assuming all are loaded to a decent velocity for their weight. IMHO, the 155 amax is a great bullet at 300yds. Double that distance and any bullet fired from a 308 can be frustrating with even a mild wind (for me). For me, the benefit of higher bc is in less wind drift. I've spent enough time gathering data for my rifle to pretty accurately put a .308 bullet where it's supposed to be as far as drop is concerned. I could probably use another 10 years or so of practice on wind calls. If you stretch the distance beyond 400 or 500, give the 178 amax a try (if available in your area).

AZAK
January 9, 2014, 02:37 PM
While it may all look good on paper/numbers, before you commit remember that each rifle sample may have it's own "preference" for certain loads/weights/lengths. This last moose season we had four different new 30-06s in our hunting group. Pre-season setting up scope/load development was eye opening in this department.

If your interest is in longer range accuracy, start playing with various bullets and loads at shorter ranges. The differences seen at 100 yards/meters will only magnify at the longer ranges; as a general rule. (Not taking wind into consideration.) Obviously if you goal is further out there you want to experiment with loads with that in mind.

Looking at bullet choices with higher BC can only help, except when it degrades accuracy. Also whether or not you are planning on hunting or just making holes in paper makes a difference in bullet selection.

Personally I enjoy loading and shooting 110 -220 grain bullets out of my 30-06. I load the different weights for different intended purposes. 110 lightly loaded is great for "recoil shy" folks, a longer range session, or introducing new shooters to a 30 caliber rifle. While my current moose load is with 200 grain loaded fairly warm but darned accurate. I have been loading 125 and 150 for predator. And recently I have loaded a few other weights just for fun. I am still looking for the "sweet spot" with all of my different weights, types of bullets, and loads; always trying to make it just a bit tighter.

I like shooting, and my interest is in accuracy. I shot 12 rounds yesterday out of one hunting rifle at the range, and 10 the time before. I make up relatively small batches to test, and I record the results so that I can compare in the future. I want my equipment to be as spot on as possible, so that I can work better on the biggest variable, myself.

To me it would be worth the extra expense of buying a number of different weights/brands/types, only if you are getting the results that you want to see for your money; and if that is worth it to you. However, first I would need to see the results for myself; and that is why I enjoy playing with many different bullets, powders, and loads. And why I have more boxes of bullets sitting on my shelves than I "need". And the ones that are "sub-par" still manage to go downrange and make a hole, or happily sit on the shelf in their boxes.

Once you have started to narrow it down, then start stretching out your distance. Slowly. When you are hitting at X yards/meters, then go to X+50 or 100. I like to have multiple targets at multiple ranges. Adjust/finetune your scope and load as you go. Always better to walk before you run. Much less frustration, much more enjoyment! Have fun! And be aware that this can be a never ending pursuit; however, you will notice that your results will improve. And if that is what you are looking for, welcome to the chase!

Feel free to take this advice as you see fit, I am but a humble amateur reloader, shooter, and hunter sharing his experiences. And true long range shooting is something that I am still working on and by no means am I an expert or even close. Still working on what many would consider "mid-range". Enjoy!

Pond, James Pond
January 9, 2014, 03:43 PM
Thanks for the suggestions.

In an ideal world, I'd like to do something similar.

Realistically I won't have the funds to undertake a comprehensive comparison because bullets and powder are so expensive. I can buy a box of 100 for $50, sure, but I wouldn't want to then consign them to a shelf after the first 25. I want to choose the most likely to work

Same with powder. It costs about $115 for 2 pounds of powder (€86), so if I find a load, as with my Amax using N135, I would feel a bit reticent about then trying N140: I'd worry that I'm going to be stuck with worse results. The devil you know and all that!! This is compounded by the fact that I can only store 10lbs of powder at any given time. 5 are already allocated to my .44 and .38 loads. Must use the remaining quota carefully!

So what I may do is first buy the Lapua bullets as they can be bought individually so I may see what some of them can do. I may even go with the Scenar over the Amax.

All that is why I am trying to make the best choice on paper before buying rather than a whole lot of expensive, and restrictive trial and error!!

The alternative is finding someone/where that is willing to sell me a few cupfuls of N140: enough to do a few OCW spreads.

The final obstacle is places to see what they can do: I have a choice between 100m, 300m and .... no, wait, that's it...:o

There is room to manoeuvre, I just have to tread carefully!!
All a bit of a pain in the rear, to be honest....

mavracer
January 9, 2014, 04:12 PM
How far out do you want to shoot? Unless you're trying to go 1000+ yards with a short barreled 308 the 155 A-Max would be good.
BTW the 155gr Lapua Scener is .508 BC

Pond, James Pond
January 9, 2014, 05:25 PM
BTW the 155gr Lapua Scener is .508 BC

You sure?!

That would be great, but the Lapua website quotes .460. Still better than the Amax, mind...

As for range. Right now I'd stuck at 300m. However, I've heard of some places for military training that are up to 1000m ans I think there is a private quarry whose owner is a shooter who lets people shoot there: that is about 600-700m.

So there is room to improve, I just don't see myself being good enough for some time, hence why I have not looked into it in more detail yet...

Bart B.
January 9, 2014, 05:41 PM
You'll have to shoot 30 caliber 155's with BC's around .500 out the muzzle at least 2900 fps to remain supersonic and stable for decent accuracy at 1000 yards.

So, with max safe pressure at about 52,000 cup (61,000 psi), how short of a barrel will do that? It typically takes at least 29 inches of barrel to do that.

Pond, James Pond
January 9, 2014, 06:15 PM
You'll have to shoot 30 caliber 155's with BC's around .500 out the muzzle at least 2900 fps to remain supersonic and stable for decent accuracy at 1000 yards.

So, with max safe pressure at about 52,000 cup (61,000 psi), how short of a barrel will do that? It typically takes at least 29 inches of barrel to do that.

My barrel is 26", my 155s can reach .460 and I expect my muzzle velocity is probably around 2650 fps.

So in other words, my 1Km goal is unachievable with my present set up.... :(

Should I be saving for a .338? :o

Won't stop me chasing 600m in the meantime though...

Bart B.
January 9, 2014, 06:37 PM
US military folks proved recently that more first shot hits on a target at 1400 meters happened with a .300 Win. Mag. than the .338 Lap Mag. 30 caliber rifles are a lot easier to shoot accurately than 33 caliber ones.

trg42wraglefragle
January 9, 2014, 06:41 PM
You can still get out to 1k but accuracy might not be the best.
If people can shoot Lee Enfield and Mosin Nagants at 1k, then you sure as hell can. You might not win any bench rest competitions, but you will get there.

Just re barrel your 308 to 260rem if you wanting better ballistics for not a huge expense.

Pond, James Pond
January 9, 2014, 06:49 PM
Hmmm... thinks...

Well, in the 2 years since I took up shooting, I have scoured and devoured every gun store and used gun webpage to see what is around and I don't remember ever seeing either a .338 or a 300 Win mag on offer...

The only larger calibres I've seen regular have been .308, 30.06 and 7.62x54 in Mosins. I did see a .270 Zastava on sale once.

I'm going to have to stick to my little .308 for now...

If people can shoot Lee Enfield and Mosin Nagants at 1k, then you sure as hell can.

I like your can-do attitude!! :D
Of course, I am still cutting my teeth at the 100m range right now, so I think there is some time before my 1000m accuracy needs any critical reviews.

All the same, I'm hoping to pin-point loads that have that potential even if I don't yet.

mavracer
January 9, 2014, 07:04 PM
You'll have to shoot 30 caliber 155's with BC's around .500 out the muzzle at least 2900 fps to remain supersonic and stable for decent accuracy at 1000 yards.
According to most of what I've seen you only need 2600 fps with a .500 bc to stay supersonic and stable to 1000

mete
January 9, 2014, 07:36 PM
Twist rate is important as the heay bullet may not stabilize. Even if the twist is correct the bullet may not stabilize until 200m.That's where you should do accuracy testing. There's a word for that stabilizing that I never can remember .:(

Tipsy Mcstagger
January 9, 2014, 08:04 PM
If you have a smartphone, download a free ballistic app and type in same info, just change the BC and look at the drop/fps/energy differences out to 1k. But, your gun has to like that bullet in the first place for it to really matter. The load matters too. I have some factory ammo that is phenomenal but when I load to the same COAL (barring primer and powder) it's completely unacceptable for target.

Jim243
January 9, 2014, 08:54 PM
There's a word for that stabilizing that I never can remember

The bullet goes to "sleep". It stops wobbling and yawing and takes on a concentric spin meaning it has stabilized. Generally in the 80 to 150 yard range depending on weight and design of the bullet. It is recommended that boat tail bullets should be used for long range shooting as where flat based bullets should be used for 100 yard accuracy. Depending on your twist rate and the weight (length) of the bullet it will have a dramatic effect on your accuracy.

Pond, you are getting into a very expensive sport when talking about long range shooting, expensive rifles (barrels & chambers as well as expensive stocks), expensive scopes, expensive ammo, and expensive finding a place to shoot those distances.

I would try to improve on your current 308 maybe with a match trigger and maybe a bedded new stock, and shoot your best at 200 meters right now.

Good luck on your quest.
Jim

Bart B.
January 9, 2014, 08:59 PM
mete, are you saying that unstabilized bullets at 100 yards that are at the outside edges of an imaginary groups at that range will start to curve towards the center of the group at 200 yards?

If so, how does a bullet in flight know where it is in that imaginary group at 100 yards so it'll know which direction to go back towards the center of the 200 yard one? For example, if it's low and right, how does it know how to go up and left a little bit?

I think the word you're looking for is "asleep." Bullets that are asleep are spining on their long axis that's parallel to their trajectory path. Their ends don't nutate or spiral around the trajectory axis. These bullets are perfectly balanced and spun at the right rpm rate to keep them this way. They look like a perfectly passed football in flight.

Unstabilized bullets that are not asleep have more drag than those that are asleep. They slow down faster than the ones that are asleep.

Pond, James Pond
January 10, 2014, 02:28 AM
Pond, you are getting into a very expensive sport when talking about long range shooting, expensive rifles (barrels & chambers as well as expensive stocks), expensive scopes, expensive ammo, and expensive finding a place to shoot those distances.

I would try to improve on your current 308 maybe with a match trigger and maybe a bedded new stock, and shoot your best at 200 meters right now.


My point about bigger calibres was somewhat tongue-in-cheek. Yes, I'd be happy to move up in calibre at some stage, but I do recognise that there is little point at this stage in my development. Aside from that I really do like my existing rifle in many ways other than just its accuracy...

As for my existing set up, I think the only think I would consider is bedding, but I've no idea who wold do this. On the plus side the CZ550 has a set trigger feature. I don't use it at the moment, but I could: that is a very crisp break. I don't see myself needing a new scope. From what I've read my 3-12x should suffice.

AZAK
January 10, 2014, 03:00 AM
All that is why I am trying to make the best choice on paper before buying rather than a whole lot of expensive, and restrictive trial and error!!
Which reloading manuals are you using? Most will have an indication as to the "most accurate" load within a given bullet type/weight range per cartridge with the "best powder" noted.

Just note that your rifle may, or may not, have the same barrel length, twist rate, etc... as the test rifle/barrel used. However, it still is a really good starting point.

A chronograph can also serve you well. Generally more consistent loads equal more accurate loads, and a chrono helps to let you know just how consistent your loads are, or aren't. Another thought that has not been brought up, single loading of cartridges vs loading the magazine. Recoil can sometimes change COAL of remaining cartridges in magazine resulting in changing pressures. (Now we are getting picky, but simple and usually free or inexpensive "fix".)

Pond, James Pond
January 10, 2014, 03:11 AM
I have a Lyman's manual (49th), I have a VV manual (3rd), I have another VV/Lapua manual, but that is older and when there is a difference I err towards the newer version. Finally, I have the Lapua loading data online.

So there is a heavy VV bias to my data choice, but then all I have are VV powders, so I suppose it doesn't hurt...

I have a chrono, but I have not used it yet. I had planned to find my OCW load, and then chrono that so that I would have the velocity readings needed for trajectory calculators. I hadn't thought to use it in the initial stages of examining charge behaviours on paper. It is also because getting the chrono set up at my range so that I can also see/shoot the targets whilst in a prone position is quite tricky.

For chrono readings, I just planned to shoot half a dozen over the chrono into the backstop, and not necessarily at the target for the sake of ease....

Bart B.
January 10, 2014, 07:06 AM
I strongly disagree with the premise that you are getting into a very expensive sport when talking about long range shooting, expensive rifles (barrels & chambers as well as expensive stocks), expensive scopes and expensive ammo.

The only expensive items are the barrel and the bullets. All else can be moderately priced and produce the same results as the most expensive stuff out there. For example, an old, well used Winchester 70 action can be had in a rifle for a few hundred dollars plus another few dozen dollars to square it up. It'll equal what a $1500 Stiller or BAT action will do on the range.

Rimfire5
January 10, 2014, 07:32 AM
Don't be concerned that you only have VV powders.
After lots of experimentation with powder choices, I have found that N140 turned out to be the most accurate powder for my two latest .308s with 150, 155, 168, 175, 190 and 200 grain bullets. I have tried Sierra, Berger, and Nosler bullets.

Also, don't conclude anything before you shoot the particular bullet in your particular rifle. The bullet shape, especially how much of the bullet is actually touching the rifling, has a lot to do with how your particular rifle performs with that bullet. BC matters after the bullet is out of the barrel, but only if the rifle likes the bullet shape and weight to start with.

My two .308 rifles are both Savages - they shoot better than I can but they have preferences for bullets, even bullets with the same weights.

One Savage has its best overall average with 175 SMK bullets then with 200, 150 and 190 SMKs all averages for all loads shot for each weight are with N140 powder and are at or under 0.48 inches. The best load for the 175s is 0.295 inches at 100 yards.

The other Savage has its best overall average with 155 Bergers and then 155 Noslers followed by 175 Noslers followed by 150 and 190 SMKs - also all with N140 powder. However, all of its top 5 averages are under 0.456 inches with the best load a 0.296 with the 155 Bergers. This Savage actually shoots slightly better on average than the first one but not with the same bullets.

You will have to determine what your barrel shoots most accurately if you are looking for accuracy alone. However, from a long range shooting perspective, you will probably find that what works really well at 100 yards may work out to 300 yards but may not hold up when you move out to 600 yards and more.

In addition to finding out that technique is crucial when you shoot at longer ranges, you might find that there is a big trade off between initial shorter range accuracy and longer range stability with the added factor of being able to read the wind. BC helps but as Bart said, the bullet can't find its way back onto the target at longer ranges if it initially strays off the intended path.

Bart is a much better source of knowledge on the long range technique part of the equation than I will ever be.

Sierra280
January 10, 2014, 11:09 AM
I mostly agree with the other posters. 308 is capable of 1000yds but there are better choices. Since the OP is a question about BC I'm a little surprised that no one has mentioned 7mm bullets. I have been trying to reach out to longer distances with my 308, and it's got me looking around for a 7mm Mag. The BC on those 7mn bullets is way above anything comparable in 30 cal (unless your interested in lobbing 210gr++ bullets downrange). IIRC a 308 175gr SMK has a BC of .502. A 7mm 175gr SMK has a BC of over .6!!

MarkCO
January 10, 2014, 11:52 AM
BC has some import, but not as much as matching the bullet, OAL, velocity to your barrel. Also, realize that some bullet manufacturer's are a bit optimistic about the BC they publish. The BC is actually variable (slightly) based on many parameters. When I have shot onto ballistics cards from 100m to 300m, I found that the BCs, for that given set of conditions could vary by as much as 0.04 from the published numbers, but usually no more than 0.015 or so.

When a bullet leaves the barrel, for some length, it is flying supersonically backwards. The gases accelerate around the slug and at some point (5 to 10 feet out) the bullet breaks the sound barrier as it surpasses the speed of the gases by the local speed of sound (why comps and suppressors "can" increase accuracy and change POI). Then you have nutation to worry about, and then somewhere downrange, the bullet goes trans-sonic again. Lighter bullets, based some on the SD and the spin rate, tend to be disrupted more due to crossing the sound barrier (both times), than heavier bullets. While there are a lot of variables with an effect, in reality, that is the biggest reason that the heavier bullets, if properly stabilized, are more accurate at range. If you do the math, a light bullet fast has a worse BC, but less time in the wind while a heavy bullet slow has more time in the wind. In most cases, if your ballistics calculations properly account for atmospheric, twist rate, changing BCs, etc. it is a wash inside the 2nd trans-sonic point.

Due to nutation, the average trajectory is kind of the shape of a coke bottle. The cone opens to a point, but then when the bullet has settled, basically you have a cylinder for a period of time, and then it reverts back to a slowly opening cone and then at the 2nd trans-sonic, a quickly opening cone.

All that said, the .308 is fine out to about 1000m, but, you will find some less expensive bullets that are just as accurate out to about 600m. I would never pick a bullet solely based on BC. I pick a bullet weight and work a few powders and bullets around my target velocity. Once I find one that works okay and call it a midpoint, then I start to vary crimp, OAL and 0.1 grain variations until I get the best I can out of that rifle for that barrel. Switch barrels, I go back to that midpoint and work back up from there. I tend to steer folks towards 155 Palmas at about 2700 fps to work on their technique and increasing range. Depending on how good you want to be, and/or how much you can get to the range, you could very well be halfway through the barrel life shooting 155s before you even need to really consider heavies and moving out to or past 1000m. Just realize, you want to keep tabs in your notebook on that "midpoint" load and maybe every 500 rounds, shoot a group at 300m. This should keep you centered in reality, help you track your improvement and most importantly, let you know when the rebarrel is due (or check your crown, change your cleaning procedures, etc.).

emcon5
January 10, 2014, 01:20 PM
It is important, however it is not the end of the world if the bullet you are using is not the best BC available. I ran some numbers, using your 155 AMAX, and since I had the Hornady manual handy, a couple other flavors of .308 AMAX.

Listed it the calculated (http://www.jbmballistics.com)drift for each bullet at a few ranges:

155 AMAX @ 2600 FPS. BC 0.435 G1 (subsonic @ ~950 yds at sea level)
10mph full value wind
300 yds: 8.4 inches, 2.7 MOA
500 yds: 25.4 inches, 4.9 MOA
700 yds: 54.7 inches, 7.5 MOA
1000 yds: 125 inches, 12 MOA

178 AMAX @ 2400 FPS .495 G1 (subsonic @ ~975 yds at sea level)
10mph full value wind
300 yds: 8.2 inches, 2.6 MOA
500 yds: 24.5 inches, 4.7 MOA
700 yds: 52 inches, 7.1 MOA
1000 yds: 117.1 inches, 11.2 MOA

208 AMAX @ 2300 FPS .648 G1 (subsonic @ ~1200 yds at sea level)
10mph full value wind
300 yds: 6.5 inches, 2.1 MOA
500 yds: 19.1 inches, 3.6 MOA
700 yds: 39.7 inches, 5.4 MOA
1000 yds: 88.1 inches, 8.4 MOA

Frankly, I am surprised how good the 155 is compared to the 178. I expected the difference to be greater.

In reality though, if you call the wind correctly, BC does not matter, provided the bullet is supersonic all the way to the target. If you call teh wind perfectly and adjust accordingly, the result is the same, a hit.

When it does help greatly is when you get the wind call wrong. For example, if you call 10 MPH @ 90º and the real value is 7 mph @ 75º, how bad will you miss?

This is how far your bullet will land from where you think it should go based on the wind call, using the same velocities and environment as above.

155 AMAX
500 yards, 8.2"
1000 yards 40.5"

178 AMAX
500 yards, 7.9"
1000 yards 38.1"

208 AMAX,
500 yards, 6.2"
1000 yards 28.7"

If it was me, I would figure out a load that works in my gun and is supersonic as far as I wanted to shoot, and call it good.

sirgilligan
January 10, 2014, 01:56 PM
If you fix all the variables and only change the BC then it will give us a feel for how much of an effect the BC has.

Value:
Zero distance: 5 yards
Sight height: 0 inches
Muzzle Velocity: 2000 FPS

This is basically thinking of a rifle as a cannon, or shooting down the barrel and not down the sights.

Time of Flight in Seconds = TOF

BC = 0.1
100 Yards: TOF: 0.18, Vertical: -5.6", Velocity: 1336
200 Yards: TOF: 0.45, Vertical: -31.0", Velocity: 1014
500 Yards: TOF: 1.59, Vertical: -368.9", Velocity: 624

BC = 0.25
100 Yards: TOF: 0.16, Vertical: -4.6", Velocity: 1705
200 Yards: TOF: 0.35, Vertical: -21.3", Velocity: 1446
500 Yards: TOF: 1.12, Vertical: -195.5", Velocity: 1014


BC = 0.5
100 Yards: TOF: 0.16, Vertical: -4.4", Velocity: 1775
200 Yards: TOF: 0.33, Vertical: -18.9", Velocity: 1705
500 Yards: TOF: 0.92, Vertical: -143.4", Velocity: 1336

These are G1 ballistics that I calculated with my Gun Log SPC app on my iPhone. I wrote the calculator myself.

The BC is all about drag, the slowing down in the atmosphere. The slower a projectile goes, the longer it takes to travel a given distance, and since it takes longer it has more time to fall and therefore it drops more.

BC is important.

Pond, James Pond
January 10, 2014, 01:59 PM
If it was me, I would figure out a load that works in my gun and is supersonic as far as I wanted to shoot, and call it good.

Then I think I need to eventually move on to N540, N550 or the like.

I will need the extra oomph to keep any bullet I choose/can find supersonic for 1000m!! With the latter a 155gr Scenar would have a muzzle velocity of 2950fps according to Lapua (test barrel, twist all the same as mine)...

Very interesting numbers though: thanks for taking the time.

If I take a step back, I think that due to my early (very early) success, or degree there of, with my OCW charge investigations, I've started finding what my rifle can do and it seems like it could do a lot for me. This means that I am now looking to what can bring me closer to my 1km goal. As another member said, beware of running before walking.

I still want to explore all these options, but the apparent time and upfront money investment for bullets and powders, I may put the brakes on a bit and stick to the 155s for now, although I want to explore the Scenar 155 HPBTs.

It may turn out that I don't need to go much further. It certainly seems the mid-weights are not the best, taking those figures as examples.

sirgilligan
January 10, 2014, 02:03 PM
Furthermore, your rifle, sight height, and zero distance would be a fixed, a constant, a value that doesn't change between loads.

What does change is the BC and the Muzzle Velocity. Those two factors will make the difference on bullet drop.

Energy is effected by bullet weight, so if you wanted a certain impact energy at a certain distance then you would have to work with bullet weight, muzzle velocity, and BC.

MarkCO
January 10, 2014, 03:34 PM
Can you run that calc again for say 0.45 to compare to the 0.5? The would give the OP a better understanding of picking one or the other just based on BC. :)

I don't even shoot pistol bullet with a .1 BC and most of the choices in a given caliber and weight vary by maybe .05 or so.

emcon5
January 10, 2014, 03:47 PM
Those two factors will make the difference on bullet drop.

I am not disagreeing with you, but need to point out that drop is not important in fixed range LR shooting, provided your sighting system has enough elevation adjustment to get on target.

As long as the sights can get you there, it really doesn't matter that the 155 AMAX takes ~42 MOA to get on target at 1000 yards and the 208 AMAX takes ~41. All that matters is the wind.

It is interesting to note though, and a good example of the importance of BC. The ~25% heavier bullet starts 300 FPS slower, yet arrives at 1000 yards faster (1.800 vs 1.859 sec flight time) with more velocity and less drop.

JD0x0
January 10, 2014, 03:52 PM
BC. How important is it?
Very.

If you want to see how dramatic BC can affect ballistics take a look at shotgun pellets or .22LR projectiles versus .338 whisper.
Most shotgun pellets start at a velocity over or around 1300fps. And .22LR usually has a MV in the 1050-1300fps range. While a .338 whisper will fire a 300 grain bullet at around 1050fps.

.338 whisper would be able to shoot over 500m
A shotgun load or .22LR would not even be close to that. Good luck getting anything on paper. The wind is going to have a field day with those low BC projectiles and they're going to lose a ton more velocity.
It takes about 200 yards for a high BC 300 grain .338 bullet to lose 50fps from the initial 1050fps MV. It takes about 20-30 yards for a 40 grain .22LR bullet fired at 1050fps to lose that same 50FPS.

sirgilligan
January 10, 2014, 04:35 PM
Can you run that calc again for say 0.45 to compare to the 0.5? The would give the OP a better understanding of picking one or the other just based on BC.

Again, zero at 5 yards, sight height at 0.0", muzzle velocity of 2000 fps.

BC 0.45
100 Yards: TOF: 0.16, Vertical: -4.4", Velocity: 1832
200 Yards: TOF: 0.33, Vertical: -19.2", Velocity: 1675
500 Yards: TOF: 0.95, Vertical: -148.5", Velocity: 1282

BC 0.5
100 Yards: TOF: 0.16, Vertical: -4.4", Velocity: 1848
200 Yards: TOF: 0.33, Vertical: -18.9", Velocity: 1705
500 Yards: TOF: 0.92, Vertical: -143.4", Velocity: 1336

p.s. Remember that ballistic drag is not linear. A projectile might be slowing at rate "X" at one instance and then "7/10ths of X" at another instance. That is a reason it is tricky to estimate the flight of a projectile.

sirgilligan
January 10, 2014, 04:56 PM
I am not a long range shooter. I do not play one on TV either.

I would think that the things that matter are:

A setup that is accurate. That means a rifle and load that are tuned to work together.
A scope that can show you the target and have enough adjustment for windage and elevation.
An accurate measurement of the wind and its actual direction. Remember that wind can move in all three dimensions, it is not just horizontal.


This is beyond my research into the topic, but I am pretty sure the rotational direction of the bullet effects the amount of wind push (deflection) if the wind is hitting the bullet directly in the side from the right side or the left.

A bullet rotating clockwise with a wind from the right would be biting down on the air and the same rotating bullet with a wind from the left would be biting up on the air. Too many variables for my brain to think of right now.

Then there is the rotation of the earth and so many other factors.

pathdoc
January 10, 2014, 06:14 PM
Silly question, and possibly obvious, but:

Are you planning to hunt animals, or merely paper targets, at long range? Because that will constrain your ultimate choice of projectile.

I would buy and read Bryan Litz's books on long-range shooting, preferably several times, regardless of which it's going to be. (You can get them from his website, as I did; if you ask, I think he even signs them for you if that's what floats your boat.) Not to say that he is the all-knowing infallible God-King of Long Range, or that his writings and conclusions are applicable to everyone, but it does give one a perspective and a base to work from.

If all you plan to hunt is paper targets, you have at least eliminated two important factors - the amount of ENERGY with which the bullet must arrive and the behaviour of that bullet when it strikes a solid object. If you're planning long-range big game hunting, the requirements suddenly become a lot more demanding and BC has to take a back seat to terminal performance considerations.

Pond, James Pond
January 10, 2014, 06:18 PM
Paper.

I don't hunt, but if I did I certainly would not shoot an animal at that distance.

If I do end up hunting I don't think I would shoot beyond 200m. In any case Estonia is very flat and heavily forested so the terrain and environment do not allow for hunting over much greater ranges.

tobnpr
January 10, 2014, 07:05 PM
I don't think the extra dough spent on high BC, VLD's is worth the dough for you.

JMHO, but my own experience is that inside 500-600 meters is not much more difficult than shooting at 100 or two...

You can't practice long-range wind calls at a couple of hundred meters. You need to actually be there doing it, at long-range. The bullet's still humming along at 500, affected by external influences but still mostly a "dial and press" deal.

As long as you've got the basics of form, trigger control and breathing down pat you'll hit consistently. It's beyond 500-600 or so that the wind really starts to move that bullet not just sideways, but up/down as well- and you won't get that knowledge from a ballistic computer.

No point wasting money on bullets where you'll never realize their potential at the range you're shooting. Load development often takes but a couple of trips to the range unless the rifle's really finicky.

emcon5
January 10, 2014, 07:26 PM
You can't practice long-range wind calls at a couple of hundred meters. You need to actually be there doing it, at long-range. The bullet's still humming along at 500, affected by external influences but still mostly a "dial and press" deal.

Well, you can't, but you can.

At sea level, a 22LR Federal 40gr Match bullet at 1080 FPS in a 10 MPH full value wind has about 3.9 MOA of wind at 100 yards, which is roughly the same as my 6.5-06 Long Range rig at 625 yards (140AMAX @ 2818 FPS). At 200 yards it has about 9 min, which matches my 6.5 at about 1200 yards.

To compare it to his .308 with 155AMAX, the 22LR at 100 has as much wind as his .308 at about 420 yards. At 200, it is roughly equal to his .308 at 800 Yards.

So you can't practice reading the wind with your .308, but you can practice.

On edit:

and you won't get that knowledge from a ballistic computer.Truth. Trigger time, trigger time, trigger time. Preferably with good coaching.

handlerer2
January 10, 2014, 09:30 PM
Mr. Pond,

I must remark, before I comment, your contribution to this forum, helps me realize how fortunate we are, us Americans to realize the liberties we do. The costs of material, and the regulations you are required to adhere to, makes your effort to this pastime most impressive.

A high ballistic coefficient is great, but at the range your limited to , it's really insignificant. The prices you quote for bullets and powder would make me consider, doing the best I could at the range you're limited to.

Flat based bullets are easier to manufacture precisely. 100yd benchrest shooters don't use BT bullets. They use flat based bullets because they are more consistent and they are less expensive.

Have you considered that the same skills that you apply to improve ability will apply at 1000yds, as well as 300yds. If you master the lower B.C. bullet, you might easier master the end bullet, at range. The most important factor is the shooter.

What I'm really getting at here, I wouldn't buy VLD type bullets for shooting at your range.

The differences in B.C. between bullets can be calculated for and compensated for enough, to get your first few rounds in sight, when you do get to shoot at long range. The rest is just fine tuning.

Pond, James Pond
January 11, 2014, 04:55 AM
Flat based bullets are easier to manufacture precisely. 100yd benchrest shooters don't use BT bullets. They use flat based bullets because they are more consistent and they are less expensive.

Have you considered that the same skills that you apply to improve ability will apply at 1000yds, as well as 300yds. If you master the lower B.C. bullet, you might easier master the end bullet, at range. The most important factor is the shooter.

First of all, thank you for confirming what my wife has long maintained: I've completely lost touch with reality when it comes to spending on my hobbies. If I'm wearing the same tired looking T-shirts 15 years from now, you'll all know why!!

Meanwhile, you raise a good point about flat base bullets. On the one hand I want to develop my ultimate LR load now and use it regardless of the distance, making me very familiar with its performance. However, you are right. If the 155gr Amax is €35 per hundred, the 150gr FMJFB is only €25.

I could no doubt get cheaper-than-Scenar Lapuas (€34 per 100 as opposed to €46) too or even PRVI (also €25/100).
If the 100-300 range is really not that demanding on the .30 calibre, then I could well practice with those. Being utterly broke after the Christmas break I at least have time to mull over my next purchase.

I think I will, nonetheless, explore the 155gr Scenar bullet as I have some already loaded up that I could incorporate into an OCW string, and others I could pull to reload at the missing string charge weights.

Jim Watson
January 11, 2014, 08:36 AM
I am not sure of your goal, whether you want to develop the most accurate load or to do accurate shooting.

But consider barrel life. I am sure Bart can say more on the subject than I know. But every shot fired in an OCW string is a shot not fired for record.

Bart B.
January 11, 2014, 08:42 AM
Given the choice of a bullet with a .550 BC that produces 1 MOA accuracy at 1000 yards and 9" drift per mph of cross wind or a bullet with a .500 BC that produces .75 MOA accuracy at 1000 and 10" drift per mph of cross wind, I'll pick the lower BC bullet with better accuracy. Shooting 10 shots with a 2 MPH spread in cross wind will produce a smaller group at 1000 with the lower BC bullet shooting more accurate.

You can practice reading the wind with any cartridge. Those with more drift per mph of cross wind makes it easier; you can see the effects of subtle changes in wind speed a lot quicker.

Pond, James Pond
January 11, 2014, 08:44 AM
whether you want to develop the most accurate load or to do accurate shooting.

Both....

But consider barrel life.

When researching calibre choice, I noted that .308 was known for its longevity, when it came to barrel life. In the multiple thousands. My rifle has probably shot something like 3-400 rounds tops, including the 100 or so I have shot through it, based on the bore gauge measurements when I bought it which a barely fired gun.

If I shoot that same quantity in a year (and that would be a busy year of shooting) I should have over a decade of life in my gun. So, for the time being, I am not too concerned about wearing out the gun.

Bart B.
January 11, 2014, 02:35 PM
Barrel life for the .308's about the same as .223 Rem and 7x57 Mauser. 2000 rounds of pristine accuracy for competition, 3000 for almost as good as pristine.

Double that for a hunting rifle. Triple that for service rifle use in combat accuracy neds.

pathdoc
January 11, 2014, 05:46 PM
I don't hunt, but if I did I certainly would not shoot an animal at that distance.

Duly noted, and neither would I, but some people choose to do so and have the appropriate terrain to exercise their hobby, so I had to cover all possibilities.

Pond, James Pond
January 11, 2014, 06:18 PM
so I had to cover all possibilities.

True and that's all good.
I just wanted to put my own shooting ambitions/short-comings in perspective.

For me I just can't imagine a point where I am so competent that I would feel willing to try further out than that.

Clearly others on here have the skill set for that, though...

5RWill
January 11, 2014, 11:11 PM
“Muzzle velocity is a depreciating asset, not unlike a new car, but BC, like diamonds, is forever.” - German Salazar

http://www.appliedballisticsllc.com/Articles/ABDOC110_WhatWrong30Cal.pdf

It's really a trade off between velocity & BC, but yes it's important.

Jimro
January 12, 2014, 12:19 AM
With a 308 you have interesting bullet choices when you are talking 1,000 yard shooting.

Bart B. might back me up when it comes to the 155gr Palma or "Fullbore" (depending on which country you happen to be in at the time) bullets at long distance. Yes they are typically launched hot, around 2,950 to 3,050 fps from long barreled 308s, but they are very accurate to 1,000 yards.

Recently an AMU shooter cleaned a 1,000 yard High Power target using Berger 185's, a very impressive accomplishment (his team mates using the same load did not score nearly as well).

For years the Sierra 168gr Match King bullet was the king of accuracy from 300 to 600 meters. It was originally designed for 300 meter Olympic Free Rifle, and it was the bullet used to take the Gold medal back from the Russians after they showed such dominance in the 50's. The 13 degree boat tail did it no favors in the transonic range and it proved unsuitable for shots 800 to 1000 meters.

Berger recently released a 168gr VLD Hybrid bullet with a very impressive BC and shallow boat tail design that makes it a competitive choice for long distance, as it has a higher BC than the 175gr SMK, and can be driven faster.

Still, in the end, any suitable bullet WILL GET YOU TO 1K. The particular BC of the bullet doesn't matter so much as whether or not it is accurate at the distance you plan to shoot.

So pick the maximum distance you want to shoot. Then pick a bullet that will get there accurately. Between two bullets being used for target work BC doesn't mean much as long as they are both accurate at the distance you are shooting.

Since you are just starting out in distance rifle work, get a whole bunch of bullets, all one brand and model, do a load workup (you've been working with the OCW method), and once you get a load that shoots sub-MOA you should start shooting at distance.

Jimro

Pond, James Pond
January 12, 2014, 04:30 AM
once you get a load that shoots sub-MOA you should start shooting at distance.

Still in the pipeline! I think it likely that I'll load up that 40.9gr as you suggested. Once my N350 has been used up, I think I may opt for a tub of N140. It seems to get more velocity being a slower powder.

If my Amax/N135 load works well, I may use the N140 on 155gr Scenars for now. Those will do for my local rifle range where 300m is max.

Handlerer2's point on FB bullets for cheaper practice is also a thought.

Ye gods.....
Even in this country with next to no choice, there are a bazillion options open to me as to which course to take! It's nuts, I tell you.

Options are nice, but that much trial and error, given my current trend of once a month shooting will take me forever!! :eek:

To think that I'd believed that a simple choice based on BC would have solved my 1K shooting ambitions, leaving only a hint of practice... :rolleyes:

It's threads like this that make how much I don't know so excruciatingly clear....

Bart B.
January 12, 2014, 03:04 PM
Sierra's 155-gr. Palma bullet is not launched "hot" as is often what lots of folks think. With a 30 inch barrel, normal loads at max safe SAAMI spec pressures will push them out around 3000 fps. So will the 7.62 NATO 147-gr. FMJBT bullet loaded to NATO pressure specs as it's often the only legal round (has to be arsenal ammo; no handloads allowed) to shoot in fullbore competitions around the world. Some overseas arsenals have bought thousands of Sierra's 155s to load in their ammo and it's very accurate so loaded.

I and others have shot cleans at 1000 yards with handloaded 155's. In my opinion, I'd rather shoot 155's from a 30" .308 Win. barrel in calm wind conditions at 1000 yards than 190s or 200s from a 28" 30 caliber magnum barrel. It's lighter recoil in equal weight rifles makes it much easier to shoot accurate. The rifle moves around much less from recoil while the bullet's going down the barrel. They strike the target much closer to where I call the shots than heavier bullets from magnums do.

Jimro
January 12, 2014, 03:14 PM
James,

If 300 meters is your max distance, even flat base bullets will do fine. I don't consider anything long distance until you are out past twice a "max point blank range" distance with a rifle.

Jimro

Pond, James Pond
January 12, 2014, 04:31 PM
If 300 meters is your max distance, even flat base bullets will do fine. I don't consider anything long distance until you are out past twice a "max point blank range" distance with a rifle.

It is. For now.

There are longer range locations, I just don't know where they are as yet.

I'll investigate the FB bullets tomorrow to check on availability.

I also pulled all my unused Amax and Scenars so I now have a few more on hand to do another OCW (Scenars) and the 40.9gr OAL sets for the Amax.