Advice on Custom 7 mm PRC Rifle with Accuracy Issues

[uppercut11]

I had a gunsmith build a 7 mm prc using a heavy contour 26” 1-8 twist carbon six barrel. I have the barrel paired with a kelbly atlas lite action and grayboe Phoenix 2 stock. I have a nightforce nx8 scope and nightforce rings on a kelbly rail. I have 210 rounds through this barrel and have tried several good powders (h1000, rl25, retumbo, n565, n570, h4831sc) with hornady 175 eldx and 180 eldm bullets. I am using ADG brass. I cannot get any load to shoot better than about 3/4 moa. For comparison I reload for several factory rifles and have them all shooting below 1/2 moa. I expected to get Accuracy at least this good from this custom build. The gunsmith bedded the action because he thought the stock pillar bedding on the phoenix 2 was causing barrel deflection, but if anything the accuracy got slightly worse.

My gunsmith is recommending that I have the barrel cryogenically treated to improve accuracy. I have read threads on here that seem to have mixed advice on this and I haven't seen anybody discuss doing this on a carbon barrel, although I suppose it would work the same on the steel portion.

Basically I am looking for any and all advice on what to do. I don't claim to be an expert reloader, but with the success I have had with several factory guns, and the combinations I have tried with this gun, I feel confident that the issue is not with the load but with the gun.

 

[jbuck88]

What other rifles are you getting sub 1/2 moa with? Do you have experience shooting magnums? Are you using a brake or suppressor? Played with different torque settings on your action screws? Shooting off a bipod or rest? If bipod are you Loading it with forward pressure? Is it causing the stock to touch the barrel? Have you tried factory ammo?

 

[Supersubes]

Weird how certain topics come up in groups. Two weeks ago zero people would have recommended or discussed cryoing carbon barrels, or any barrels for that matter, to fix bad accuracy. Now its become a thing.


Did the gunsmith chamber this barrel, or is it a carbon six prefit?

 

[jbuck88]

Forgot to ask if there was a old guy at the range shooting a pre-64 winchester looking down his nose at you?

 

[spife7980]

Use a non hornady bullet and see if that changes things, Sierra matchkings aren’t fancy but are reliable.

 

[diggler1833]

Yep. Might be a tad more, but I'd give a Berger bullet a try before I started messing with the barrel.

 

[kthomas]

Is cryo'ing barrels becoming en vogue on someplace like Reddit?

Before you send your barrel off to get cryo'ed, I would read this cautionary tale: https://www.snipershide.com/shooting/threads/carbon-barrel-cracked.7229562/

I would agree with the other suggestions in regards to trying other projectiles before trying anything else.

If Bergers or SMKs don't work out, then its time to try other options. Based on what I'm hearing you say about your gunsmith and his suggestions, I'm not getting very good vibes there...

 

[uppercut11]

What other rifles are you getting sub 1/2 moa with? Do you have experience shooting magnums? Are you using a brake or suppressor? Played with different torque settings on your action screws? Shooting off a bipod or rest? If bipod are you Loading it with forward pressure? Is it causing the stock to touch the barrel? Have you tried factory ammo?

Savage 116 in both .300 win mag and 7 mm rem mag both with no brake or suppressor, Remington 700 .223, Savage ultralight in 6.5 CM, Seekins Element in 6.5 PRC (suppressed). I have been shooting it off a lead sled for load development. I have a brake on this one. Stock has plenty of barrel clearance. Tried factory Hornady precision match and shot around 1.5 MOA and precision hunter around 1 MOA.

 

[uppercut11]

Weird how certain topics come up in groups. Two weeks ago zero people would have recommended or discussed cryoing carbon barrels, or any barrels for that matter, to fix bad accuracy. Now its become a thing.


Did the gunsmith chamber this barrel, or is it a carbon six prefit?

The gunsmith chambered it.

 

[uppercut11]

Yep. Might be a tad more, but I'd give a Berger bullet a try before I started messing with the barrel.

OK. I have had good luck with hornadys in my 6.5 PRC and 6.5 CM. Use Nosler Accubonds in some others.

 

[Supersubes]

The gunsmith chambered it.

Cryo treating it will do nothing. Contact Carbon six.

 

[uppercut11]

Is cryo'ing barrels becoming en vogue on someplace like Reddit?

Before you send your barrel off to get cryo'ed, I would read this cautionary tale: https://www.snipershide.com/shooting/threads/carbon-barrel-cracked.7229562/

I would agree with the other suggestions in regards to trying other projectiles before trying anything else.

If Bergers or SMKs don't work out, then its time to try other options. Based on what I'm hearing you say about your gunsmith and his suggestions, I'm not getting very good vibes there...

I appreciate the input and the link. I had never heard of cryo treatment on barrels before he mentioned it so have been looking into it a bit. I wondered if something like what happened in the link could happen with carbon.

 

[uppercut11]

Cryo treating it will do nothing. Contact Carbon six.

I sent carbon six an email today with the same info I posted here. I will see what they recommend.

 

[jbuck88]

Savage 116 in both .300 win mag and 7 mm rem mag both with no brake or suppressor, Remington 700 .223, Savage ultralight in 6.5 CM, Seekins Element in 6.5 PRC (suppressed). I have been shooting it off a lead sled for load development. I have a brake on this one. Stock has plenty of barrel clearance. Tried factory Hornady precision match and shot around 1.5 MOA and precision hunter around 1 MOA.

The lead sled is going to be the first thing to suggest to get rid of. Next try it with and without the brake. Might be a source of harmonics, usually able to tune it out with load development though. Then I'd try to mess with different torque on your action screws. Again with it being bedded might not make an appreciative difference but worth a try.

 

[uppercut11]

The lead sled is going to be the first thing to suggest to get rid of. Next try it with and without the brake. Might be a source of harmonics, usually able to tune it out with load development though. Then I'd try to mess with different torque on your action screws. Again with it being bedded might not make an appreciative difference but worth a try.

What would the problem with the lead sled be? I have always used it in the past.

 

[jbuck88]

What would the problem with the lead sled be? I have always used it in the past.

I've only used one once and could not get as good of a group as without it. Could have been a lot of different factors, not saying it was 100% the lead sled. But there are lots and lots of people who say they're having accuracy issues with them. Google lead sled accuracy issues and you can read up and make your own conclusion.

 

[Chickentoast]

Agree with above - try different levels of hold pressure - a few of mine require specific holds to get the bugholes. Hadn't shot one of them in a while, and couldn't get it to shoot the load in my notebook... then saw my own writing next to the load, free hold for this load. Next group, ragged hole. Worth a try.

 

[diggler1833]

OK. I have had good luck with hornadys in my 6.5 PRC and 6.5 CM. Use Nosler Accubonds in some others.

Me too. One particular bullet design might suit this barrel better for you though.

 

[Long Range 338]

Agree with testing different bullets. Sierra and Berger are excellent choices. Sometimes a barrel just doesn't like a certain component and by simply changing one thing it suddenly starts shooting. See what Carbon Six has to say but unless you find a major defect in the barrel they will be telling you to contact you gunsmith anyway.

 

[uppercut11]

Update - I ended up calling Carbon6 and talking with Gene for almost an hour. Long story short, I sent him some pictures and it is not actually a Carbon6 barrel. Best guess is xcaliber. I called the gunsmith and he is not sure how he got barrels mixed up but he should be ordering me a Carbon6 barrel for my at his expense to make it right.

 

[Scotch_egg]

Always insist on the end of the barrel being cut off and coming with the rifle. That way the smith is in no doubt what make the barrel is.

Mixing up a barrel is not great though.

 

[redneckbmxer24]

Update - I ended up calling Carbon6 and talking with Gene for almost an hour. Long story short, I sent him some pictures and it is not actually a Carbon6 barrel. Best guess is xcaliber. I called the gunsmith and he is not sure how he got barrels mixed up but he should be ordering me a Carbon6 barrel for my at his expense to make it right.

I’d ask if you can pay the difference to get a Proof. Carbon6 barrels are shit, they use McGowen blanks.

 

[jbuck88]

Update - I ended up calling Carbon6 and talking with Gene for almost an hour. Long story short, I sent him some pictures and it is not actually a Carbon6 barrel. Best guess is xcaliber. I called the gunsmith and he is not sure how he got barrels mixed up but he should be ordering me a Carbon6 barrel for my at his expense to make it right.

I have zero experience with carbon6, but have had great luck with proofs as well.

Sucks to get the run around from your smith, really hope it was a honest mistake. However, the cynic in me says no. I would definitely be done with him.

 

[FisherT&C]

If it's the wrong barrel it could be the wrong twist.
Check the twist with the cleaning rod method; it's quite accurate if done properly.
Here's Larry showing one way to do it.

 

[shootertom]

Try some different bullets, I have had some rifles that simply don't like hornady bullets. If you are looking for a great hunting bullet, try the 165 Sierra Game Changers.

I'm on my 6 or 7 carbon six barrel and have had good luck with getting them to shoot very well. They have a little longer break in period than a Proof, but I can get just as good of accuracy.