Proof barrels

  • I’m working on load development for a 6.5 SAUM with a proof barrel. After barrel break in the rifle was showing real promise with groups in the mid .2’s to low 3’s. I loaded a fine ocw test and that’s when it went to hell. Groups started opening up to 1.5 moa. You’d get one little small group then that same load would turn out a 1.5 group a few minutes later. I checked the action screws, scope mounts and rings, even changed chassis, as well as optic and rings with the same results. Seems to do best with a clean barrel but after 10 or 12 rounds it’s back to shooting like shit again. I’ve never messed with a carbon barrel so wanted to see if anyone on here has ever had an issue like this. The current load is 140 VLD’s over H1000 with CCI-250 primers. I have some retumbo I can try if all else fails.

  • Get a scope in there? I wonder if something found its way into your rifling?

    I've heard of proof barrel accuracy issues before, but I've not heard of one shooting in the .2's and then blowing out to 1.5.

  • @orkan

    I plan on running a bore scope through it Monday. I agree it’s a odd behavior I’ve not seen anything like this before. The majority of the increase in group size is vertical, most all of the groups string vertically not really much horizontal if that means anything to you.

  • You pull some velocity numbers?

  • @orkan

    Yes for the most part they looked good, Es and sds in the single digits for most loads. Of course there were some charge weights that were higher which is typical.

  • Tried retumbo today, all groups from 6 different charge weights were under .5 moa. 61.2 centered up on a node at 2968 fps ES of 4 and SD of 1.8. I have not gone and measured the target but groups appear to be mid .2’s or so.

    Obviously this barrel just did not like H1000. It would shoot it ok for a couple rounds then it would get crazy inconsistent. Goes to show how the most popular powder for a given cartridge doesn’t always work.

  • @bull81 Glad you got it sorted. Yes, sometimes a guy actually has to work for it. ;)