Can accuracy improve with use?

[LocoGringo]

Here's the situation: I recently built a new AR-15 and the barrel maker guaranteed sub-MOA accuracy with match ammo.

I followed their recommended break-in procedure of shooting 60 rounds no faster than 1/second (I shot MUCH slower than that while zeroing and tuning). All groups were shot from a front rest with a rear bag. At the end, I loaded some HPR 75 grain match and shot for 2 5-shot groups. The groups were both larger than 1MOA. I loaded 5 rounds of Federal Gold Medal Match 69 grain and shot a group. Then I loaded the same magazine with ammo from the same box and shot it from another AR-15 that has the same scope, trigger, pistol grip and buttstock.

The first rifle that guaranteed sub-MOA shot a disappointing group that measured 2.47" while the group from the other rifle measured .78".

My question is this...is it possible/likely that the new rifle might "settle in" and improve with use? Both rifles are for 3-gun competitions.

 

[ford8nr]

The 'barrel' is guaranteed sub-MOA, doesn't say anything about what you attached it to. Poor lower to upper fit, furniture attachment amongst other things will affect your OVERALL accuracy.

 

[LoonWulf]

Look for out of alinment parts. Gas block touching handguards, loose muzzle device, barrel not square in reciever. Ars are easy to put together but sometimes something will get just a little out of alingment, or youll get an unsquare part.

 

[DRYHUMOR]

Not every barrel likes the bullets you like to use. When you shot the 60 rounds, did you clean the barrel as you shot?

A trigger can make a world of difference also.

 

[tarosean]

confused 2 rifles. One you built... then the other is identical or ???? built or purchased?

 

[azrocks]

I believe it's common for stainless barrels to require a break-in period before achieving their accuracy potential. I assume that's what you've got as I'd be surprised if a manufacturer would make such a guarantee on a chrome-lined barrel.

That said, I don't see a barrel break-in taking groups from 2+ inches down to sub-moa.

Are both rifles free-floated? Is the rifling rate the same?

It's always possible you got a bad barrel. But it's probably much more likely it's something else.

 

[LocoGringo]

Tarosean, both rifles are Frankenbuilds with the purpose of shooting 3-gun competitions. The original rifle (Rifle #1) is phenomenal, but heavy, so I built a second rifle (Rifle #2) with the idea of shooting just as well, but being a little more compact and lighter without increasing recoil or muzzle rise. Rifle #1 is more traditional with a NiB M16 carrier and standard recoil spring and fixed gas block. Rifle #2 (the one that is "guaranteed less than 1 MOA" accurate) has an adjustable gas block, lo mass carrier and reduced power recoil spring. Rifle #1 has an 18" barrel and Rifle #2 has a 17.3" barrel. Both barrels are rifle length gas systems and are melonited, but from different manufacturers. Rifle #1 has a .223 Wylde chamber, 1:8 twist, 5R rifling. Rifle #2 is 5.56 NATO chamber, 1:7 twist and something called Single Edge Land rifling. Rifle #1 is also a Mega billet upper/lower while Rifle #2 is more traditional forged upper/lower. Rifle #1 is 9 pounds 2 ozs complete (scope, mount and everything except a loaded magazine) while Rifle #2 is 8 pounds 3 ozs, so I was successful in shaving a full pound off of the weight between the 2 rifles. The only thing I have tested so far is accuracy.

Both rifles have Timney 3# triggers, Ergo pistol grips, Burris MTAC 1.5-6 power scopes, and Magpul ACS-L buttstocks. Both barrels are free floated and I know the gas block is not touching the handguard on either rifle. Still wondering if a barrel can "settle in" with use or if accuracy is "fixed" and only gets worse with use over time.

With the FGMM group for rifle #2, it's possible I had a "flier" that opened the group from 1.50" to 2.47". I understand that the reticle of a MTAC isn't a precise reticle, but 1 rifle turned in a .78" group with that reticle/ammo/shooter/target compilation and the other "guaranteed" barreled rifle turned in a 2.47" group with an identical compilation.

Thanks for all of the replies so far.

 

[wally]

If they "guarantee" it, find out what ammo they use, and if your's can't do it with that ammo, send it back.

 

[desidog]

What is the twist rate of the barrel?

...cause if it's 1:9 it probably won't do well with either bullet weight you used. Try 55's.

 

[Sunray]

"...and improve with use..." No.
The manufacturer guarantee 1 MOA with Federal Gold Medal Match? Most such 'guarantees' are BS anyway. It only applies to the ammo the manufacturer used under the conditions on his test range. However, a good match grade barrel means you can work up the load to match standards. Those standards are not 1 MOA though. 2 or 3 MOA is good enough.

 

[carbine85]

I've always had the best luck with 69 gr ammo at 100 & 200 yards.
I would expect the best accuracy from the 1:8 with the 69's.
Who's barrel is it anyway?

 

[LocoGringo]

Who's barrel is it anyway?

Sorry about the odd post. I was on a company computer last night and it won't allow me to type anything...I only get to be a voyeur.

The barrel for rifle #1 is an AR Performance barrel. The barrel for rifle #2 is a Rev-Arms barrel.

 

[GooseGestapo]

Last year about this time I bought a Rock River Arms National Match AR. Wilson 1/8" Stainless barrel.
It took about 300rounds before accuracy settled in. Shot a 6" 10 shot group at 600yds with 80gr Sierra MatchKing. From prone position! Iron sights.

I have a .257Roberts built in 1983 with an E.R.Shaw light taper barrel. It too took ~300rds to settle in.
Give your barrel some time to lap in.

 

[wally]

It took about 300rounds before accuracy settled in.

Is that the barrel getting better or you getting better

Triggers definitely seem to improve with shooting.

 

[The_Next_Generation]

Tarosean, both rifles are Frankenbuilds with the purpose of shooting 3-gun competitions. The original rifle (Rifle #1) is phenomenal, but heavy, so I built a second rifle (Rifle #2) with the idea of shooting just as well, but being a little more compact and lighter without increasing recoil or muzzle rise. Rifle #1 is more traditional with a NiB M16 carrier and standard recoil spring and fixed gas block. Rifle #2 (the one that is "guaranteed less than 1 MOA" accurate) has an adjustable gas block, lo mass carrier and reduced power recoil spring. Rifle #1 has an 18" barrel and Rifle #2 has a 17.3" barrel. Both barrels are rifle length gas systems and are melonited, but from different manufacturers. Rifle #1 has a .223 Wylde chamber, 1:8 twist, 5R rifling. Rifle #2 is 5.56 NATO chamber, 1:7 twist and something called Single Edge Land rifling. Rifle #1 is also a Mega billet upper/lower while Rifle #2 is more traditional forged upper/lower. Rifle #1 is 9 pounds 2 ozs complete (scope, mount and everything except a loaded magazine) while Rifle #2 is 8 pounds 3 ozs, so I was successful in shaving a full pound off of the weight between the 2 rifles. The only thing I have tested so far is accuracy.

Both rifles have Timney 3# triggers, Ergo pistol grips, Burris MTAC 1.5-6 power scopes, and Magpul ACS-L buttstocks. Both barrels are free floated and I know the gas block is not touching the handguard on either rifle. Still wondering if a barrel can "settle in" with use or if accuracy is "fixed" and only gets worse with use over time.

With the FGMM group for rifle #2, it's possible I had a "flier" that opened the group from 1.50" to 2.47". I understand that the reticle of a MTAC isn't a precise reticle, but 1 rifle turned in a .78" group with that reticle/ammo/shooter/target compilation and the other "guaranteed" barreled rifle turned in a 2.47" group with an identical compilation.

Thanks for all of the replies so far.

Try putting the suspect barrel in the Mega Upper and then pin it to the Mega lower, and tighten everything down to spec. Being machined, not forged, means they have probably been more thouroghly checked for trueness than your forged mix and match set. Im willing to bet that could solve your accuracy conundrum.

ETA: Accuracy can improve with use. Copper buildup will plateau eventually, and will result in more consistency shot-to-shot. That said, Ive fired sub half-minute groups from a brand-new barrel. So, yes, accuracy can improve as a barrel is shot in the sense that your bore conditions will become more consistent. However, you should be able to remove all fowling from an accurate barrel, fire a shot, clean again, fire, and on and on, and it should still shoot well because of the consistency between shots - not because its dirty or clean.

Sorry if that was confusing, its past my bedtime...

 

[redneck2]

I would tend towards "accurate from the start". But, I've had two CZ's that both needed over a hundred rounds before shooting well. My .204 was awful. Tried all kinds of loads. Groups were 4-5". Dunno if I found the magic load or it just settled in, but since I've shot multiple groups of sub .5's.

Same with my 452 .22.

 

[LocoGringo]

Next Gen, I like the idea, but I REALLY don't want to have both rifles disassembled and the barrels swapped, especially since the new rifle barrel is cerakoted FDE.

I've got a club match on the 19th which I'll give the new rifle a try to see if it handles and shoots faster. Those are 2 aspects I hope to see superiority to rifle #1.

Part of the reason I'm so reluctant to deal with the company that made the barrel is because it has been a miserable experience dealing with them to get the upper in the first place. I made the original order with them the first week of June and finally got the last part for assembly last month. It was an endless litany of excuses, delays, and fraud.

 

[1stmarine]

I would go "debug" the problem starting from the most obvious to the less obvious.
- Find out what match ammo was actually used by the manufacturer to claim submoa. Not all ammo is the same, the same way not all chambers are the same.
- Properly assembled parts.
- A trued / tight fit receiver can make a big difference.
- Quick / rough inspection of the bore and chamber.
- Check head-space.
- Loose optics all things properly setup (you would not believe how many times installation can be an issue)

Might look for less obvious.
- Check free bore to precisely know what chamber you got. Inspect chamber closely.
- Make sure the twist is the advertised (test the actual twist)
- Make sure bore is concentric. Sometimes makers make mistakes taking the wrong twist barrel or failing to properly index
the barrel in the chuck before cutting barrel or chamber.
If you find something wrong ask for a replacement.

Manufacturing mistakes are not frequent but they do happen. I have found a good share over the years.