600-1000 yds

[CS86]

I've been fallowing this and its been an interesting read. I was interested in hearing how many rounds through a gun would show diminishing effects to accuracy. I realize this can make a difference on which caliber you are loading for and how you are loading. One thing I was curious about is what the major factor is that wears out the barrel? Is it the pressure or friction or both? The reason I ask is because I was wondering how much more life would you get from a barrel if shooting lead instead of jacketed bullets?

[Bart B.]

Throat erosion from hot gasses having the same effect as a cutting torch blasts away microsized particles from the origin of the rifling; the leade as it's called. That's where the barrel throat tapers down at a 1 to 2 degree angle past the groove diameter to the bore diameter. The rate of erosion opens up the diameters in that area causing more bullet jump to the rifling. The rate for 30 caliber service rifles is about .001" diameter increase for every 1000 rounds fired. And for every .001" diameter increase, the leade moves about .010" further down the barrel.

When the erosion gets to the point where it's no longer the same amount all the way around, that tends to deform bullets unevenly and they're more unbalanced than when new. So, when they leave the muzzle, the centrifugal forces makes them jump off the bore axis a bit.

That erosion rate's determined by peak pressure as well as powder burning temperatures. Powders with higher burn temperatures erode the barrel more per 1000 rounds than those with lower ones, all at the same pressure level.

I and others have cut the back 3 inches off of 28" center fire target rifle barrels and put them in another rechambering it. Such barrels shoot just as accurate from the get-go as little, if any, bore erosion happens 3 iinches down the bore from the origin of the rifling. I knew a top ranked smallbore rimfire match shooter who set his barrel back 2 inches every 30,000 rounds. It shot just as accurate at 20 inches long having started out at 26 inches. Yes, even rimfire .22's wear out barrels.

[Brian Pfleuger]

Originally Posted by Bart B.

Fewer than 10% of the very best of them put their first shot within 6 inches of dead center.

It's amazing to me, how much more difficult it is as the range increases. Little old me, with (relatively) no experience, with a bone stock gun and cheap scope can easily hit a 3" target at 300 yards. (As can the best in the world, obviously, and then some). It seems so completely counter-intuitive that the difficulty would increase THAT much.

Bart, have you ever put together or seen a graph depicting average group sizes at each distance, shot by "the best"? I'm curious what sort of equation it follows. I'm guessing it's exponential to some degree.

[Clark]

Brian Pfleuger
It's amazing to me, how much more difficult it is as the range increases.

Me too.
I have not figured out the definitive math.
But I can guess that the hoop shooting high probability range for the world's best basket ball player divided by the range for an average high school basket ball guard is probably equal to the world's best rifle shot divided by MY max range is the same.

World's best rifle/ my rifle = ~900 yards / ~500 yards = ~1.8
World's best basketball / high school basket ball = ~21' / ~12' = ~1.8

[Jim Watson]

A friend took some successful deer hunters out on his laser surveyed range, 100-600 yards. They found 300 metres, the metallic silhouette pig distance, to be a considerable challenge and anything more pretty much out of range.

We read of those long range kills on game because they are difficult and unusual, not routine.

[MarkCO]

^ True.

I put about 1000 rounds downrange at known distances with my .260 before I started practicing shooting on the prairie at unknown distances and ranging. Even with considerable practice and well above average skills pulling the trigger, reading wind, knowing my DOPE and animal behavior, there are distinct limitations. I put out 1500 rounds before I shot an animal beyond 505.

I saw the video of the .243 @ 688 on a woman's first elk...sorry, but I just don't agree with the risk that was taken.

[Bart B.]

Brian, yes, it's exponential. Muzzle velocity and BC spreads across the bullets cause about 1/10 MOA increase in vertical group size for each 100 yard segment past the first one. All bullets of the same make and model do not have the exact same BC; it varies a percent or two due to their unbalance they have from the factory plus anything added by deformation from firing. And those micro-speed subtle cross, head and tail winds at even 1/4 mph move bullets up and down, left and right and change their ground speed a few fps; there's no such thing as perfectly stable air outdoors.

After watching long range competitors shooting scope sighted, shoulder fired rifles slung up in prone, as well as my own observations doing it myself over the years, here's what happens when we are using rifles and ammo that shoots no worse than 1/4 MOA at 100, 1/3 MOA at 300, 1/2 MOA at 600, and 3/4 MOA at 1000 yards properly tested for accuracy. Average 20-shot groups on paper by top classified folks in a 600 yard match, 1.7 MOA shooting scores of 199 and 200. At 1000 yards, groups average about 2.1 MOA scoring 198 to 200 points. The record 20 shot strings' groups are about 1 MOA at 600 and 1000; that didn't happen until about 15 years ago.

Such is life holding a 3/4 MOA area on the target with your sight, not putting the rifle back into your shoulder exactly the same from shot to shot and missing those near invisible subtle cross winds' 1 mph change in speed that moves the bullet 8 inches to one side from where you wanted it to go. Which is why the group on paper may be well under 1.5 MOA in the vertical axis, but near twice that horizontally.

Don't forget, groups are always zero MOA at the muzzle. Aren't they?

[Metal god]

never mind

[Clark]

Bart,
See if I got this straight.
You have put 20 shots into 3.325" at 800 yards, and that is great precision, but you won't shoot at a deer at 800 yards, because you don't have enough first shot accuracy?

[Metal god]

The record 20 shot strings' groups are about 1 MOA at 600 and 1000; that didn't happen until about 15 years ago

.-------------------------------------------------------------------

20 shots into 3.325" at 800 yards,

These two quotes seem to fly in the face of one another .

I thought that 3.325" group was done at 600yds with iron sights and thats about 1/2 moa not about 1 moa . Was that not shot at an official event ?

[JD0x0]

You have put 20 shots into 3.325" at 800 yards, and that is great precision, but you won't shoot at a deer at 800 yards, because you don't have enough first shot accuracy?

You can't predict whether that animal will move in the over 1 second of flight time of the bullet. It's too much risk for 99% of hunters to be able to call the shot ethical. Also you can't control the wind down range. If there is even a slight change, or unknown crosswind, which gusts, it could turn a good chest shot into a terrible gut shot. And being at 800 yards, it's unlikely you'll be able to make a follow up shot or be able to track the animal because of the distance.

[Bart B.]

My 3.325" 20-shot groups was shot at 800 yards, 5:30 to 6:00 am in virtual dead calm winds. Rifle was supported on soft bags at fore end and stock toe; nowadays a typical F-class position. Reticule in the 20X scope bounced around on the target well inside a 1" diameter circle; pretty good holding for an older man at the time. I'd fired 1 or 2 shots to center the group on the 3-foot square 1/4" thick foam board, let the barrel cool down to ambient temperature, then shot 20 rounds about 20 to 30 seconds apart. Just testing ammo, not in a match.

[Metal god]

See how word of mouth/Internet changes things . I thought for sure I had those numbers right . still impressive shooting . What was the ammo and rifle ?

That target is looking pretty old . Was that down in hieroglyphics

[Bart B.]

Clark, yes, I won't take a shot at game at long range, even with a zero MOA shooting system. I'm not all that great estimating wind corrections nor range. People in the 1970's had .308 Win rifles that tested in the 2 inch size 20-shot groups at 600 yards, but the best of them kept 10 shots inside 9 inches shooting from prone.

About those first shots. . . In the hundreds of matches 600 yds and more, my first shots fired striking somewhere in the 1 MOA inner ring, only a dozen or so have done that. 3 or 4 times it was in a team match when the coach gave me the correction for wind. The others were more luck than skill. Many of those first shots were 2 MOA to one side. One was almost dead center on the 1000 yard target 10 feet to the right after totally forgetting to make a guess for a wind correction.

Metal God, that 20-shot group on foam board's 20 years old and has been handled quite a bit. Flimsy, too with all those holes in it. Rifle was a single shot rifle built on a 4-lug single-shot Paramount action from England. It has a 3.6-pound trigger. Fitted with a 30" long, 4-groove, 1:13 twist Kreiger barrel SAAMI spec chambered for the .308 Win. Cases were once fired, unprepped WCC60 match cases full length sized in a standard RCBS die with neck lapped out to .002" under loaded round neck diameter. Loaded with 45.3 grains of IMR4895 over an RWS primer and under Sierra's prototype 155-gr. bullets seated out to set back about .010" when chambered.

[tobnpr]

It's amazing to me, how much more difficult it is as the range increases.

Hitting a 1-1/2 minute plate at 600 isn't even a challenge- and I don't consider myself to be more than a bit above average in skill, and with an "OK" rifle...

1000 yards is a different ballgame. Bullet velocity decreasing, drop, drift, all much more so than in the first 600. Wind calls, esp. in a challenging environment, can be downright frustrating. The only cure is trigger time, and in my case, trying to glean some pointers from the experts there that understand how to read the conditions.

[Bart B.]

Hitting a 1-1/2 minute plate at 600 isn't even a challenge- and I don't consider myself to be more than a bit above average in skill, and with an "OK" rifle

Slung up in prone without a rest 20 times in as many minutes?

[tobnpr]

Not my words...

Nor did I see where Brian referenced your specific methodology.

Little old me, with (relatively) no experience, with a bone stock gun and cheap scope can easily hit a 3" target at 300 yards. (As can the best in the world, obviously, and then some).

Seemed that his was a "generic" reference to increased difficulty in making hits
with range.

[std7mag]

What about the old tried and trued, 30-06???

If you wanted a little more velocity from it, you could always do the AI route.

Don't know what the average barrel life is from one.

Can't remember how many boxes of rounds I put through my old Savage.

[Bart B.]

While the veneral .30-06 was popular in match rifles for 60 years, it took only 2 years in the 1960's for the .308 to replace it. Its better accuracy led to so many unbreakable ties, the NRA had to make the targets' scoring rings about half as big.

[jsflagstad]

A couple of years back my dad called me and asked if I wanted to take a long range 1000 yard shooting clinic with him at his gun range. Being an avid shooter and never shooting at that distance before I jumped at the chance. Now I really don't own any real "Nice Expensive" rifles, but the ones I have shoot well. My safe is full of H&R Handi's, Savages, Marlins, and a Tikka. Yes, some may argue that the Tikka is a higher end gun, but I bought it when Gander was first dealing in them and I got it brand new (stainless) with rings for just over $350 maybe 10 years ago.

Anyway, I had to make a decision on what gun I should select for the long range clinic. I narrowed it down to 2 of my 7mm selections, either my 1990 K-Mart purchased Savage 110 7mm Rem Mag, or the more recent purchased aforementioned Tikka chambered in 7mm-08. The Savage is topped with a Weaver 3-9x and the Tikka with a Nikon 3-9x and both very good shooters.

I decided to take the Tikka, as I would be shooting quite a few rounds throughout the day and the recoil is considerably less than that of the mule kick from the 7mag Savage.

Next, it was time to work up a load for the 7mm-08 for the upcoming event. I selected a match grade Sierra boat tail of 140 grains pushed by a moderate charge of Varget (great stuff), lit by a bench rest primer to get a MV right around 2800 fps. Next stop, the humbling range....

Range day was a great time. We started at 300 yards and moved back from there. 300,400 and 500 yards were quite easy to produce acceptable groups, the real challenge started at 600 and beyond when the wind came into play. As we got out to 800 yards, my max 9x on my scope seemed like that little scope I had on my Daisy air rifle when I was a kid.

Even though my scope seemed a bit under powered, I was able to make it work and started shooting some good groups at 800. It was at this point that I realized that the spotter I had was as equally as important as I was running the rifle. He was giving me the corrections and reading the wind gusts telling me when to shoot and when not to.

When we arrived at 1000 yards from the 800 yard berm, I didn't know what to expect. I got the rifle dialed in in a few shots, let it cool, and dropped 5 consecutive shots in the bullseye! Wow was that ever cool to accomplish that! I can honestly say that without the coaching the spotter I had, who was an accomplished long range shooter there is no way I could have been real successful much passed 600 yards. That said, the pit man down spotting the targets said my bullets were dropping to subsonic just prior to hitting the target so if I shoot that range again I'd heat my load up a bit to try to attain a 3000 fps MV.

One of the coolest things about the clinic was the handshakes at the end when I shook the instructors hand and was congratulated for being the only person in the class to actually produce a group at 1000 yards, it was then that he looked down at the rifle in my hands and said "this was the rifle you were using?" looking a bit surprised. He asked what caliber it was and what kind it was which was pretty cool.

Yes a 7mm-08 in my eyes is a remarkable cartridge when it comes to weighing recoil, flat shooting, knock down power and range. Is there a better cartridge out there? Quite possibly, the 280 Rem actually is quite intriguing to me, but I think the recoil will be a bit more stout. I have shot many deer with this rifle and in the field I normally shoot Federal Fusion 140 grain ammo and have yet to have a deer take even another step after being hit. I have taken a few with my reloaded ammo but did have a bad primer at one time that cost me a wallhanger buck so I went to the factory ammo for hunting.

So in closing, am I an expert? No. Should you listen to me and run right out and buy a 7mm-08? Well, I guess if that's what you want sure.. Really, I'm just an average guy that was looking for the same as you, a rifle that could perform in the field and hold it's own on the range. Is mine the best? Heck no, there are guys shooting as well as I did with open sights at 1000 yards. It's still a heck of a long ways, a little over 1/2 a mile actually.

Hope this helps someone, sorry for the long wind...again, I'm not an expert, just sharing my experience and my opinion.

JSF

[mohr308]

I'm glad I asked this question, with everyone's input I'm learning a lot of info here. I never would've thought about barrel life! That's important to me! So from all of this the 7mm-08 is looking very promising, and I've turned away from things like the .338 rifles. Thanks everyone.