Have almost 4000 through the barrel

[cw308]

The barrel I have is a Rock Creek M24 5R rifling 11:27 twist . I'm shooting 168 grain Sierra over 40.8 grains of IMR 4064 308 caliber. The rifle is still shooting very accurate , I shoot one Rand at a time , 30 rounds in one an a half hours , 3 ten shot groups . What round count do you think I can go before accuracy drops off . Average around 600+ per season .

[Colorado Redneck]

Good read written by Bart B.

https://www.thehighroad.org/index.ph...l-life.786330/

[Bart B.]

What is your "very accurate" average group size? What range?

From the link above in post #2 .....

[stagpanther]

I'm copying and printing out that chart--thanks for that. Do you find this chart is fairly consistent regardless of powder typically used for a given cartridge?

[Nathan]

That chart looks super conservative....I believe it would have my 5.56 shot out around 3000 rounds.

To me, shot out is when accuracy becomes too poor for the guns purpose. It would be hard to wear out a 300yd deer rifle.

In a 6mm PPC trying for world class accuracy, 100yd 0.25” groups in good conditions is near shot out.

A varmint rifle that can’t hold 0.75 moa at 300 yds is getting near shot out. The trouble is a new varmint rifle is not much better that this. I think this condition is how you get shot out at 3000 rounds. Still, put a new Krieger on this, true the action and bed it up right, you will see 0.5 moa groups that hold under 0.75 moa for maybe 6000 more rounds.

[hounddawg]

depends on the shooter - what may be acceptable accuracy for me would be totally unacceptable for a top shelf BR competitor. Also seems to depend on the individual barrel. I had a pair of .260 Rem barrels both from the same manufacturer both same length, same steel etc. One went almost 2.5 - 3K rounds and could still give me consistent .5 MOA 5 shot groups, the other barrel's groups started to expand at the 1500 mark. I change when the groups star climbing above .7

When I suspect a barrel is going I get one or more of my friends to shoot a few groups. There are several high masters in my club. If they get bad groups I replace the barrel

[stagpanther]

Pretty depressing to think my 338 Lapua barrel won't make it to even 1000 shots! Currently my favorite cartridge.

[cw308]

Bart B
The ranges in my area are maximum 200 yards so thats the distance I always shoot . I shoot 3 ten shot groups in average of 2 hours with a Rem 700 308 my group size is .5 , I stopped load testing after finding a round that worked and only concentrate on shooting form , the rifle still shoots but don't want it to crap out in the middle of my shooting season . I don't compete just like shooting with friends in the warm months . Accurate Ordanance is who I use for barrel changes . Wish I got into benchrest sooner , my eyes and being able to remain as steady aren't what they use to be . I'm sure the rifle is better then the groups I'm putting out but I can still keep up with the Young guns . Back to my rifle , I use the ChargeMaster 1500 and dump onto the GemPro 250 for a 40.80 powder charge IMR 4064 under a 168 Sierra MK , case headspace is .001 - .002 no more or less with a .002 jump . Would send the rifle for a barrel change in the winter . Last barrel I changed had 4000+ didn't know if it was time because it also shot well but was the original LTR 20" stock barrel . I would like to get another season with this one because finding another reload starts all over again . Finding the load is fun but finding that perfect load my take one third of barrel life , tweaking here and there . Getting spoiled I guess , wish good barrels last forever .

Chris

[Bart B.]

Originally Posted by Nathan

To me, shot out is when accuracy becomes too poor for the guns purpose.

I agree.

My chart is for centerfire match rifles at 100 yards starting out with 1/4 MOA average shot unrestricted free recoil, then worn out at 3/8 or 50% bigger

Double the round count for varmint rifles starting out at 1/2 MOA.

Triple for big game rifles starting out at 1 MOA

Quadruple for service and combat rifles starting out at 2 MOA .

It varies +/- 10% or more with powder heat indices, less with hot burning powders.

It varies a lot more across hand held rifles and marksmanship skills. The. NBRSA benchrest 100 yard, eight 10-shot group average/aggregate record is .1899 inch; largest single group is larger, probably close to .3000 inch.

[Bart B.]

Originally Posted by cw308

Bart B
The ranges in my area are maximum 200 yards so thats the distance I always shoot . I shoot 3 ten shot groups in average of 2 hours with a Rem 700 308 my group size is .5 ,

Is that average .5 inch, .5 MOA or .5 foot at 200 yards?

[T. O'Heir]

Define "shooting very accurate". Accuracy to a hunter is not the same as it is to a 1,000 yard target shooter or a 200 yard Bench Rest shooter. So your .5" will be shot out already to a BR guy. It'd be fine to any target shooter. And a hunter would be on here bragging about it.
You're not shooting Bench Rest. You're shooting ~ 4 rounds per minute off a bench. Different things.
"...case head space..." Cases do not have head space.

[cw308]

Half inch ( .5 ) at 200 yards.

[Bart B.]

Originally Posted by cw308

Half inch ( .5 ) at 200 yards.

First time I have heard of that small of an accuracy average for a 308 Win barrel after that many rounds. Are the biggest groups about 3/4 to 7/8 inch?

Well done!!!!

[cw308]

Bart B
How long do you think I have with this barrel ? I clean the barrel out at the range with Ballistol , when I get home I use KG - 1 and #9 works for me , no copper fouling .

[Bart B.]

I have no idea how long it will last. It already seems to have longer life than Sierra Bullets 308 Win test barrels that are replaced when 10 shot groups with QC reference bullets first go over 1 inch at 200 yards at about 3000 rounds from rail guns.

[cw308]

Bart B.
Are the biggest groups 3/4 to 7/8 ? No , the rifle is I'm sure more accurate then the 1/2" that I can shoot. , When a shot goes out of the group it's me and I know it . Before with the stock barrel I was getting also tight groups opened up to 3/4" after 4000 round count , by the end of this season I'll be at 4000 , just hate to change it prematurely , l know what I have , I've been lucky with these last two barrels and It's the only rifle I shoot , my one and only . The rifle started it's life as a Reminder 700 LTR 308 with a fluted 20" 12 twist barrel , I changed the stock to the full size 700P HS Precision stock , bedded the action with Devcon steel added a Jewell trigger set at 10 ounces . Ken Farrell mount and rings , $ 300. Bushnell scope 6.5 x 24 x 40 shooting 200 yards only it fine . When it was time for a barrel change , sent it out to Accurate Ordanance , they completely blueprinted it and skim bedded the Rock Creek M24 5R SS 20" barrel 11:27 twist . Shoot alot of weapons in my time but this is my favorite . Don't even have the itch to shoot another .
h to shoot another .

[Bart B.]

Originally Posted by cw308

Are the biggest groups 3/4 to 7/8 ? No , the rifle is I'm sure more accurate then the 1/2" that I can shoot. ,

If groups average .5 inch, what is the size of the largest one used to calculate that average?

When a shot goes out of the group it's me and I know it .

If shot groups average .5 inch, some groups are bigger due to variables in the ammo. Some groups are smaller. Human variables can add or subtract from that of the rifle and ammo.

[Jimro]

The M24 barrel has proven very reliable.

The Army standard (at least back when we were still shooting M24s) was no greater spread than 1 MOA for a five shot group with M118LR, at 100 yards, to remain in service as a sniper rifle. If the rifle could not maintain that level of accuracy free recoil from sandbags, we sent it back for a new barrel.

We generally saw accuracy drop outside of acceptance starting around 8,000 round, although one barrel lasted over 12,000 rounds before we had to send it back for a new barrel.

Given the low rate of fire, I expect the OP's barrel still has a few thousand rounds to go before accuracy is unacceptable for his purposes.

[cw308]

Bart B
Most all the groups are 1/2" in 9 groups of 10 shots two or three groups may have a pull shot , not the rifle or ammo just me , it happens some times and you know when it happens last weekend it shot six rounds in a horizontal group line .308 by .5" the others were 1/2" high because I couldn't see the holes . I shoot at a 1" out lined square box with a 1/4"black outline , the string of shots was on the bottom line reason my POA also it started getting hot . I generally aim with the crosshair horizontal lines even with the bottom line of the box and the vertical cutting through the center , this day the rounds were hitting even with the hairs as it became hotter the hit slightly higher as normal. I'm sure you being more steadier then me the groups I feel would be tighter , when a shot goes out of the group making it 3/4 and you know why , It's not the rifle or what you feed it .

Jimro
I would hope to get 8000 out of my M24 , I do baby it . I shoot very mild loads 40.8 of IMR 4064 , guess time will tell .
Thanks guy's for time and input .

Chris

[Bart B.]

Most all the groups are 1/2" in 9 groups of 10 shots two or three groups may have a pull shot , not the rifle or ammo just me

The statistical probability for that many groups being .50 inch is a tiny percentage.

Something ain't kosher.

How are those 10-shot groups measured? Got any pictures?

[cw308]

Bart B
I keep 2 log books , one with the target shot that day the other with date , measurements , weather conditions and cases used , I use 3 different brands of brass HSM , FC and ADI , shoot one brand each week . All trimmed to the same 2.010 each firing , all full sized to the same case headspace .001 or .002 .Same powder charge , same bullet same BTO . I use to measured the height and length of the groups with the caliper but now I just eyeball the group , I'm not competing so I don't have any skin in the game I just like to shoot with friends . I'm old school don't know how to post pictures , I like my flip phone . I'm shooting off a rabbit ear heavy sand bag and a Harris fixed Bi Pod , I use a piece of carpet under the legs , the bench is concrete . No shoulder pressure heavy cheekweld . My left eye is my dominant eye so I shoot left handed with a right hand bolt , my thumb on my shooting hand is pointing forward no pressure . No secrets here just works well for me after plenty of trial and error.

[old roper]

Bart, You do know that NBRSA record you post about was shot by Rail gun.

[Bart B.]

No it wasn't. A light varmint class rifle in 30 PPC was used:

http://bulletin.accurateshooter.com/...th-0077-group/

[old roper]

Bart, You did post this "It varies a lot more across hand held rifles and marksmanship skills. The. NBRSA benchrest 100 yard, eight 10-shot group average/aggregate record is .1899 inch; largest single group is larger, probably close to .3000 inch.

[Bart B.]

Originally Posted by old roper

Bart, You did post this "It varies a lot more across hand held rifles and marksmanship skills. The. NBRSA benchrest 100 yard, eight 10-shot group average/aggregate record is .1899 inch; largest single group is larger, probably close to .3000 inch.

OK.