I have a new dasher. I fireformed new Lapua 6BR brass with a .257 expander & neck down for tight fit. I used cream of wheat on top of 14.5 grains of Titegroup secured with a half patch folded. The first 40 were not fully formed (obviously) but otherwise uneventful. The next 40 (another day) were in the same stage of forming as the first, BUT there were very noticeable 1 or 2 concentric rings on the outside shoulder when looking from neck to primer. Fellow shooters remarked that it could be the result of chatter when it was reamed. I know 100% that my gunsmith would not let a mistake out of his shop. Further inspection of first 40 showed some type of ring marks after first bullet shootings with 32 grains Varget & 105 vld's.
I took the rifle to him along with the brass and he noticed a build up in the chamber which at first seemed like cream of wheat but it was not. It seems to be brass. It wouldn't come off by any method. He may re-ream. ALSO there was a lot of brass on the boltface. All of the brass was SS pin tumbled after necking up/down and chamfering so there were no bits of brass lurking in the case. What is causing the brass build-up? How to correct?
I took the rifle to him along with the brass and he noticed a build up in the chamber which at first seemed like cream of wheat but it was not. It seems to be brass. It wouldn't come off by any method. He may re-ream. ALSO there was a lot of brass on the boltface. All of the brass was SS pin tumbled after necking up/down and chamfering so there were no bits of brass lurking in the case. What is causing the brass build-up? How to correct?
