How clean?

[jelenko]

When looking for 1/2 MOA accuracy, how much does carbon left in the grooves impact accuracy? Rifle is 223, shooting 70+/- gr bullets.

I clean after every range session [50-120 rounds] and inspect with a borescope. Even after cleaning with a bronze brush and patching out, the grooves in the first 3-5 inches are covered with carbon after a few hundred rounds. Using Iosso/JB, the lands come clean and the middle third of the grooves show metal. If the lands are clean but the grooves are covered, at least in a couple times, getting at least the middle third of the groove seems to have improved group size. Does that seem right?

But, what about the carbon on either side of the middle of the groove? Is that carbon going to impact noticeably the 1/2 MOA groups?

 

[Retired Grunt]

I was having problems at matches, 1st string was always in the 180's. I was joking with the Match Director about it, he thought for a second and asked me how often I clean my barrel, my immediate response was 'After every time I shoot'. His response was just clean it every 300 -350 rounds.
I shot 8 matches before I cleaned it this summer, my scores went up consistently. Is it due to not cleaning or I just shoot better now? I honestly don't know.

I can't believe the Army taught me such bad habits. Lol.

 

[Forum Boss]

My 6mmBR was up around the 900 round mark, with regular patching and Wipe-Out foam (inside warm bore) every 60 rounds or so. However bronze brushing was never part of the regular regimen -- because the ES/SD was low and the gun always shot great. But as the round count was getting up there, we did a bore inspection with a Hawkeye and yes there were dark streaks in the grooves (not thick, more like a old felt pen streaks). I was all ready to do a hefty clean with IOSSO etc., then my buddy Joe said "why don't we shoot it first?" We did, and he drilled a 4-shot group in the high ones followed by a 0.21" 5-shot. Conclusion -- barrel was fine. Don't neglect your bore. However, ultra-aggressive cleaning may be counter-productive. Let the target tell you what works.

 

[jelenko]

My 6mmBR was up around the 900 round mark, with regular patching and Wipe-Out foam (inside warm bore) every 60 rounds or so. However bronze brushing was never part of the regular regimen -- because the ES/SD was low and the gun always shot great. But as the round count was getting up there, we did a bore inspection with a Hawkeye and yes there were dark streaks in the grooves (not thick, more like a old felt pen streaks). I was all ready to do a hefty clean with IOSSO etc., then my buddy Joe said "why don't we shoot it first?" We did, and he drilled a 4-shot group in the high ones followed by a 0.21" 5-shot. Conclusion -- barrel was fine. Don't neglect your bore. However, ultra-aggressive cleaning may be counter-productive. Let the target tell you what works.

Got it. Thanks!
It was trying to let the target decide that led me to wonder about how clean.
In the two 'trials' so far, having the grooves completely covered with carbon produced a larger group. I'll try repeating the trial a few times.
FYI. I'm using Mr2000 which seems to be leaving more hard to remove carbon than, say, 8208. TAC is looking similar to MR2000 but not quite as dirty.

Would the smaller bore of a 223 tend to build up carbon faster?

 

[acloco]

EVERY......every.....barrel is like dating somebody new.

 

[DngBat7]

Found this video today. Thought it was pretty informative.

 

[Rsadams]

EVERY......every.....barrel is like dating somebody new.

It costs alot and before it's over you will end up hating it on one level or another....lol Sorry couldn't resist....

 

[jelenko]

Found this video today. Thought it was pretty informative.

Yes! Spot on.
Of course, for 'cross the course' we really would not notice 30 to 50 thousandth MOA difference.
In our stage that has the highest demands for accuracy we're looking for ~ 1/2 MOA. Less is better but won't make much difference on the target when shooting from a sling.

My take aways. When in doubt, clean it. With a new barrel, keep it spotless at first to confirm accuracy.

 

[INTJ]

Like has been posted, every barrel is somewhat different and many approaches work.

When I "heavy clean" a barrel I like everything out of the bore with the exception sometimes of a little copper in the grooves near the muzzle.

When I " regular clean" I want all carbon and copper off the lands. Having a little in the grooves is fine.

 

[garandman]

I can't get my bore clean without a bronze brush.

Still breaking in/doing load development so we will see if a clean bore is essential to accuracy.