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Gunsmithing Bore condition help

gilk

Private
Full Member
Minuteman
Nov 5, 2009
113
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I have new hand lapped barrel chambered in 223 match (long throat) that refuses to shoot and during inspection with a bore scope I noticed a lot of denting and a few pits/gouges in the bore. This barrel has less than 300 rounds shot thru it and will not shoot any factory ammo consistently under 1moa and struggles to do much better with hand loaded ammo. I've tried several bullet/powder combinations and every now and then ill get a couple 1/2 -3/4moa groups but I can never reproduce those results with the same ammo/conditions on different days. I've sleeved and lapped the bolt (action previously trued) and re-bedded the gun twice to get an absolute stress free bedding job. Tried several proven scopes. I've ruled out everything but the barrel. Do the pictures below show a crap barrel or is that not out of the ordinary?
 

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Given the long throat are you talking meant for 80-90 grainers? And have you tried any of those in your reloading efforts?
 
Yea I’ve shot 80gr eldm’s and 85.5gr Berger hybrids from 0.010” - 0.080” jump with H4895 and Varget and nothing does well.

It’s a CB rem-age prefit that was headspaced and installed by the same gunsmith that trued the action and has built several excellent shooting rifles for me in the past. I took it off and reinstalled it and rebedded the rifle with great results then it went back to bad. I’ve had issues with another barrel from this maker and they worked very hard to correct the issues. I’m trying to exhaust all of my options before I have to return another barrel.
 
The first pic below was after I reinstalled the barrel and sleeved/lapped the bolt. Had a horizontally strung alternating poi so I redbedded the rifle and got 2 good 1/2moa groups. The next 2 range trips with the same load opened back up to over 1moa. It’s very inconsistent.
 

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Looks like a chrome lined bore with the chrome flaking off to me , with all the pits and bad spots no way I'd call that a new barrel .
 
It’s not new new, it’s had about 250-300rnds shot thru it but it is stainless.

I didn’t understand why there appeared to be a shiny streak in some of the grooves. Idk I’d that was an optical illusion or there was a high spot or narrow land in that area?
 
see if your gunsmith has a set of .223 reamer bushings or gauge pins to push down the bore to check for tight spots or a reverse taper. I suspect two things that should be ruled out, a oversize bore at the muzzle from lapping or a crooked chamber. The first can be remedied by shortening the barrel and the second probably means a scrap barrel.
 
I have been considering getting a lead slug and checking for variations in bore diameter like Gordy Gritters suggests but I’ve never done it and I’ve been putting it off hoping I could solve the problem another way. I think I’ll have the gunsmith take a look it tho.
 
I had a Harrels precision radial brake installed by my gunsmith but I mostly shoot it suppressed. I’ve shot it with a brake, no brake, and suppressed but haven’t seen any difference in accuracy. The suppressor usually tightens up groups on my other rifles tho.
 
I would check and maybe re-crown the barrel. Check bolt thrust with loaded virgin factory ammo or virgin factory brass. If those check out then I would say a new barrel. Chasing anything else would
be a time thing and chances are it couldn't be fix anyway.
 
The crown appears to be ok.

How do you check/measure and evaluate bolt thrust?
 
A few questions.
What your cleaning technique? Barrel looks dirty.
What do you mean by sleeved and lapped the bolt?
What yardage are you shooting?
What is the contour of the barrel?
What type of conditions are you shooting under? Are you using wind flags? Are you shooting off a bench with a rest or a bag?
Are you jamming the bullets into the lands, what your neck tension?
Have you tried other powders or increase your charge weight? What's the speed of the bullet? Have you tried other bullets?
What type of dies are you using?
There are a lot of factors of why your rifle is not performing to your expectations.
It hard to fix a problem with limited info.
Thanks,
Thud
 
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