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Old February 8, 2013, 04:10 PM   #1
Pond, James Pond
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.308 handloads and accuracy: please clarify.

It has been a while since I last touched my .308. Not had the time, until today that is.

Anyway, the last time I raised the issue of my 155gr A-Max and Scenar handloads I had explained that none of my handloads had struck home, even at 100m. At the moment they are 38gr and 36.5gr respectively of N135.

So I took some member's advice and upp'ed my charge form the starting load to a mid-load. This time I fired another 5 of each (A-Max and Scenar). Again the accuracy was poor, but at least I could see where they were hitting. They were going straight but dropping horribly.

So, is this just down to a lack of power?
Do I just need to increase the charge?

I guess what I'm trying to ask is if it's feasible that all this was just down to bullet drop because of a lack of velocity?
It just seems surprising that a relatively light 155gr bullet could drop by 7-9 inches over just 100m.

By comparison, I shot about 20 Norma Jaktmatch training rounds, also 155gr. They flew pretty straight and I managed some average groups (I'm still a hideous shot...). This at least tells me that both the scope and the rifle are doing their job, even if I'm not doing mine.

So how can I get these fine target bullet to fly true so that I can start to get my own technique to improve too?
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Old February 8, 2013, 04:30 PM   #2
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I don't know that much about Vihtavuori, but I can tell you that for something like Varget, that's a pretty light charge weight. None of my handloads really started waking up until I got up in the 42-44gr region. There were some one off good groups down there at 39-40gr, but they weren't consistent. My magic charge of Varget seems to be 43.2 to 43.6gr, regardless of bullet weight (150 to 190gr).

Either way, I think you need to load 10 each starting at 40, then working up in .5gr increments to 46 while watching for pressure signs. That'll get you in the ball park of where you need to start fine tuning your charge weight in finer increments and seating depth.

Make sure you're shooting off at least a bipod and rear bag or a front and rear bag. Not knowing anything about your rifle, I'd also just throw "take your time between shots" in there for cold bore vs. hot bore. My remington 20" SPS doesn't care about cold vs. hot, So...
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Old February 9, 2013, 03:01 AM   #3
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Thanks for those pointers. However I will say that Varget loads appear to be bigger and my only concern is that the listed max load for the Scenar bullet (both the bullet and powder are from Lapua) is 40.7gr. At 36.5gr, I am already 35% of the way to max loads. I hope I don't need to push it too close to max to get a decent load.

I equally hope that the A-Max will come into its own soon as these are the cheaper and more abundant bullet . At the moment it seems to be the less accurate of the two...

By comparison, the Jatkmatch Norma round had noticeably more punch in the shoulder....
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Old February 9, 2013, 07:26 AM   #4
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In checking the following:

http://www.lapua.com/upload/download...uideed9eng.pdf

I see that 155's in a .308 need about 40.7 grains of N135 to shoot 'em out at 2738 fps. That's the same as what you've mentioned as max.

Any load more than 10% below max in rifle cartridges is way too much. In the .308, that's not enough to fully expand the case and can lead to head separation. I'd not go below 5% under max for a starting load.

A common and excellent load with Varget under 155's is about 45 grains.

How do you know those bullets drop 7 to 9 inches at 100 metres? Normally, it's about 3.
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Old February 9, 2013, 08:50 AM   #5
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"A common and excellent load with Varget under 155's is about 45 grains."

I didn't know this was common, but it sure shoots fine in a couple of my M-14's.

And who has been hogging all the Nosler 155 blems?? I need more - only have 200 left. Could trade for Lapua rebated bullets (D46?).
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Old February 9, 2013, 11:27 AM   #6
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It is possible that your particular rifle might not like the slightly faster N135 powder with that weight bullet.

Lapua's reloading site indicates that the minimum load for N135 with Lapua Scenar 155 grain bullets is 34.4 grains (2254 fps) and the maximum load is 40.7 grains (2638 fps).

In my .308 using 150 grain SMKs, I have had the best results with N140 using 42.3 to 43.1 grain loads depending upon the seating depth (my rifle has a 24 inch barrel).
For 150 grain SMKs, Vihta Vuori recommends N140 loads range from 40.4 (2467) to 47.3 (2851 fps).

I have had my best results with N140 with 168 grain bullets with loads in the 40.6 to 42.8 grain range depending upon the bullet and the seating depth.
Vihta Vuri recommends N140 loads with 168 SMKs from 36.2 (2247 fps) to 42.8 grains (2558 fps).
I have also had results almost as good from H4895 and Varget with 150 to 168 grain bullets.

The even slower N150 powder in my rifle doesn't match the performance of the N140 or H4895. The same for Reloader 15 which is also a slower powder. Apparently, my rifle is not a fan of powders that are slower than N140, H4895, and Varget.
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Old February 9, 2013, 11:29 AM   #7
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Quote:
How do you know those bullets drop 7 to 9 inches at 100 metres? Normally, it's about 3.
Firstly I should highlight my scope is zero'd at 100m using the Jatkmatch rounds.

My sighting target was stuck on top of a military silhouette target that much bigger.
I'd put a few holes with the Norma rounds in my own target and, knowing that my handloads were unpredictable, I looked for an area that was untouched.

So I aimed at the "head" of the silhouette and saw hits in the "chest" area. Similarly, later I aimed at the "hip" area and saw hits on the lower leg and target margin.

Those distances were easily 7-9" below point of aim.
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Old February 9, 2013, 11:30 AM   #8
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Quote:
Originally Posted by Pond, James Pond
Thanks for those pointers. However I will say that Varget loads appear to be bigger and my only concern is that the listed max load for the Scenar bullet (both the bullet and powder are from Lapua) is 40.7gr. At 36.5gr, I am already 35% of the way to max loads. I hope I don't need to push it too close to max to get a decent load.
Why don't you want to go to max loads? You're barely at starting loads right now. Max loads aren't dangerous, as long as you work up and see no problems. Just an increment or two below max is often found to be very good.
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Old February 9, 2013, 12:00 PM   #9
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Quote:
should highlight my scope is zero'd at 100m using the Jatkmatch rounds.
Different loads will shoot to different points of impact. Fact of life.
The JaktMatch 150's were also going out at ~2,650fps while your handloaded 155gr//VV135/38.0gr were doing ~2,450.

Not that big a deal -- but that's where they impact in contrast (probably due more to barrel whip dynamics than anything else.)

Find the most accurate load combination (not necessarily the fastest).
Then adjust the scope.
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Old February 9, 2013, 02:02 PM   #10
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Quote:
Why don't you want to go to max loads?
Just because once there, there is not much margin for error. It is just a load I am wary of, that's all.

Quote:
Find the most accurate load combination (not necessarily the fastest). Then adjust the scope.
And there in lies the catch 22!!
I use my scope to monitor accuracy, and yet I can't rely on these loads to be accurate to my point of aim.....aaarrrgghh!

Quote:
It is possible that your particular rifle might not like the slightly faster N135 powder with that weight bullet.
I hope not.
I bought N135 over N140 basically by flip of coin, but I've got a whole tub of it and nothing else to use it on so I really hope I can get these loads to work. Legally, I can only keep 9lb of powder, total, so I don't want 2 lbs of powder I can't use sitting around...

Fingers crossed.
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Old February 9, 2013, 02:08 PM   #11
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My bad.

Adjust the load for maximum precision (smallest group size), the adjust scope to move the group to where you want it.

Ignore the exact impact point (within reason) until then. (Although you could adjust the scope at least get in the ballpark
if way off. Then do final adjust later.)
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Old February 9, 2013, 02:13 PM   #12
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Quote:
Adjust the load for maximum precision
So you mean get a load that keeps hitting the same spot, in relation to my point of aim, even if not the actually where I'm aiming?
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Old February 9, 2013, 02:15 PM   #13
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Can any of you advise on a max N135 load for 155gr A-Max?

I can't remember where I got my load data from!!
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Old February 9, 2013, 02:23 PM   #14
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There's plenty of margin for error at max loads. You're not going to blow up any modern firearm before you see some pretty obvious warning signs with the brass, primers, and/or extraction effort.

Yes, find a load that shoots little groups and then adjust your scope. Think of it this way... If you'd used these reloads FIRST, you'd be asking "Why does this factory ammo shoot 6" high!"

Vihtavuori data is available online:

http://www.lapua.com/en/products/rel...ata/relodata/5
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Old February 9, 2013, 02:30 PM   #15
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Quote:
Vihtavuori data is available online:
Seen that page already, thanks, but the AMax is not listed.

Either way, I'll bump the Scenar load up to 39gr for next time, and hopefully I'll also know the max load for the Hornadys and take that 1 gr below max for now.

I can work up incrementally from there.
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Old February 9, 2013, 02:38 PM   #16
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QuickLoad says 42 gr of n135, topped with 155 amax is warm (47k psi), but OK.

Maybe a compressed load. 2600fps.
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Old February 9, 2013, 04:18 PM   #17
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To confirm, Hornady's manual says 35.8 grains minimum to 42.3 grains maximum of N135 under the 155 grain A-max seated to 2.800" COL in a Hornady Frontier case with Winchester WLR primer. This is to go from 2200 fps to 2700 fps. That low end is pretty low.

I generally like N135. It's my favorite 150 grain bullet powder in .30-06 for the Garand because it's bulk density is low enough that it fills the case better than many powders, yet is still fast burning enough to produce low gas port pressure relative to the velocity it achieves, and these are reasonable but not high for that gun.

You'll have to tell us what other components you are using. What your rifling twist is, your barrel length, etc.

As has already been stated, the low point of impact (POI) is due to the muzzle having deflected upward at the start of recoil, then begun to swing down again by the time the bullet exits. This imparts a downward drift to the bullet, causing low POI. You need to get the bullet out of the muzzle faster.

Don't worry too extremely about exact maximum pressures. You have to know the way the pressure standards work is based on a standard deviation of 4%. That's pretty big. Most handloaders pretty easily do better. Figure that for your N135 loads to be out that far out, only 19 in 20 would have to have their powder charges within a grain of your nominal charge weight. 5% could be more than a grains from your nominal charge weight. I don't know any powder measure that would throw N135 that badly. A high speed powder dispensing system like manufacturers use, yes. But not one running at the speeds a human arm can go up and down and with a pause while the next case lines up.

Since you are still learning to shoot, I suggest you try Dan Newberry's OCW system as a starting point for your load development. If you get really good, there are refinements Mr. Newberry eschews, but at your current level of shooting you won't benefit from benchrest loading techniques. The first thing is to get you on paper. As suggested, you want the same POI from your rounds, then to adjust your sights. If the commercial match shot well for you, then it is likely other loads that work well will not be far from that same POI with the same weight bullet.

For some suggestions about how to shoot better in general, you may find this article interesting.
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Old February 9, 2013, 04:54 PM   #18
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Thanks for the advice and links as well as the load data both you and Dave P provided.

Quote:
You'll have to tell us what other components you are using. What your rifling twist is, your barrel length, etc.
Bullets: either 155gr Scenar, or 155gr A-max
Primers: No. 200 Large Rifle Primers from CCI
Cases: My used Norma cases from the Jaktmatch, plus a handful of cases I picked up at the range.
Rifle: CZ 550 Standard, 1:12, 24" barrel

As for my shooting technique, I think I need to spend a lot more time with my .22 as making a pig's ear of it in .308 is expensive!!
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Old February 10, 2013, 09:26 PM   #19
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James,

Based on barrel time calculations for different 24" barrels in the past, I'm going to guess you'll fine a sweet spot somewhere from 40.2 grains to 41.7 grains. Step up in .3 grain steps using Dan Newberry's round robin method and see what you find. This is on the assumption your Norma cases weigh around 172 grains like Lapua .308 cases do.

Try weighing the cases you picked up before reloading them. After .300 Winchester Magnum, the .308/7.62 has more internal capacity variation from one headstamp to the next than any other chambering. I have a bulk purchase of Winchester cases that average 156 grains, and a 1000 new IMI Match cases that average 186 grains. That 30 grain difference, if you assume the outside dimensions are the same, would amount to close to 3.5 grains of water capacity difference, which takes about 2.1 grains of powder charge difference to get to the same peak pressure. That comes out to -1 grain of powder for 14 grains additional case weight.

-1 grain of powder for each 12 grains additional case weight and -1 grain of powder for each 16 grains additional case weight are both recommendations I've seen in the past for various chamberings. The actual number varies some with the powder and the chambering, but for .308, with most powders used in it, that 14 grains of brass per grain of powder will be a ballpark adjustment number to use. Case exterior dimensions don't match perfectly, and I usually figure the case weight difference only reflects internal capacity difference with a consistency of around 20%. But that's close enough to help you adjust a charge for a different headstamp.

Norma cases I have are all very consistent, like Lapua cases. I would develop your loads all with that one headstamp first. If you really want to eliminate variables, try to select a load work-up set that are withing a span of about a grain and a half of one another. One trick I like to use is to line them all up on some big graph paper with weight on the horizontal axis to look for peaks. The result can reveal that brass was coming off different sets of tooling whose output clusters around one peak. Select all your test cases from one tooling group to improve consistency further. A weight span of 1.5 grains is equivalent to approximately 0.1 grains of powder, which is as much resolution as powder scales normally have, so anything in that range should be about as good as it gets. Later, after you find the center load range, you'll probably discover such sorting no longer helps. But you have to find that midpoint first.
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Old February 11, 2013, 01:49 AM   #20
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My accuracy load with VV-N140 and the 155gr Scenar was 45.2 grains in Lapua brass. Same velocity as Lapua factory 155
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Old February 11, 2013, 07:56 AM   #21
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James Pond asks:
Quote:
So you mean get a load that keeps hitting the same spot, in relation to my point of aim, even if not the actually where I'm aiming?
Yes. Benchrest shooters in the USA do that all the time so they won't shoot away their tiny aiming point.

Once you've found a load that's clusters all the shot holes in the smallest area, adjust your scope's elevation and windage knobs so the shots center around your point of aim. All that does is move the optical axis of the scope such that its reticule centers were the shot hole are clustered at.
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Old February 11, 2013, 12:42 PM   #22
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Exactly.

First, find the load that gives best precision (smallest group).

Second, adjust the sights so that load also gives best accuracy (coincidence of point of aim with point of impact).

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Old February 11, 2013, 03:38 PM   #23
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Thanks for all the further pointers and explanations!

I have since made up 10 rounds of 39gr N135 with the Scenar and10 rounds of 41gr for the A-max.

Looking at your diagrams, Unclenick, I can say that my shooting pattern looks diappointingly like the bottom right picture, whilst I'd really like to be in the top left box.
I am truly diametrically opposed from my ultimate goal...

I feel lot of work is lying ahead if this is my 100m performance and I want to push 1000 one day!! Oh boy....
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Old February 11, 2013, 03:59 PM   #24
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In QuickLOAD the Scenar wants about an even 1 grain less than the V-max due to its greater length, so 39.3 to 40.7 grains of N135. I notice the Vihtavuori manual calls that upper load maximum with that bullet in Lapua cases with, presumably, their own primers. So you've got a little room to move, yet.

If you don't mind, would you weigh a few of your Norma cases and post the average. I'd just like to verify the comparison to the Lapua.

Also, if you have time, do a case water overflow capacity measurement. Take an average weight case that has been fired but not yet decapped or resized. Weigh it. Then fill with water level with the mouth (no meniscus; also no air bubbles inside and no water drops on the outside) and weight it again. Provide the difference in the two weights plus the length of that case. From that I can use QuickLOAD to adjust the guesses for the size of your chamber.
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Old February 11, 2013, 05:07 PM   #25
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Quote:
If you don't mind, would you weigh a few of your Norma cases and post the average. I'd just like to verify the comparison to the Lapua.
The water displacement values will come later: all my cases are de-capped already, but in the mean time, here are my case weights for Norma brass in grains:

1:166.3
2:164.5
3:165.2
4:165.7
5:165.9
6:167.5
7:166.3
8:166.0
9:166.1
10:165.6

Avg: 165.9gr per case

HTH
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