Proof 6.5 SS comp Contour - Lapua Brass Sizing Issues

[ktm131rob]

All,

I have a 6.5 cm proof comp contour proof barrel in a TL-3 action. For the last few months I have been shooting this setup with a K&P barrel spun up and fluted by LRI.
I was shooting this barrel due to weight at the NRL. It is a hammer. Recently I switched back to the proof barrel for weight it historically had shot equally well. I have been shooting Lapua brass in the LRI barrel with no issue, some light pressure signs but no issues.

Today I took a small batch of brass out to shoot to verify that my load would work in my proof barrel. I sized 1 chunk of brass to the proof chamber and set the shoulder back .005. Loaded 50 and went to the range. Straight away 5/10 rounds would not chamber. Upon returning from home I dived in, checking case length, shoulder to chamber measurements and after two hours of screwing around I determined that around the 200th mark of the case my brass was bulged .002. Some brass would some brass would not have this issue, I played with my dies thinking that this was a setup issue but after trying a Hornady and a RCBS die I had the same issue in the proof chamber. Took all that brass and it chambered perfectly fine in the LRI barrel.

Have any of you had this issue with a proof chamber? if so what did you do? Is a different die needed for the tight chamber?

I have a match next weekend and figured this setup would yield results. I can switch barrels but id love to be able to run Lapua brass in this chamber in the future.

Thanks,

 

[spife7980]

Had the issue using old 6 creed brass that was sized with a Redding bushing die in a proof barrel, a forester die sized the base an extra thou and it works fine now.

 

[ktm131rob]

Thanks, I had some other feedback elsewhere that matches what you are saying.

 

[Lawnboi]

Just differences in chamber, I wouldn’t necessarily think a die would fix your issue.

My LRI chambered rifles hammer, and generally have been a little tighter to the min headspace. This has caused brass fired in other chambers not to work

 

[ktm131rob]

Very interesting. This is good info.