I picked up my new Savage 12 Benchrest yesterday from the gun store. It's chambered in 6mm BR. I took it home, swabbed out the filthy bore with several wet patches (Shooter's Choice bore cleaner) and several clean dry flannel patches. Mounted the scope rail and the scope and took it out to break it in.

I had purchased two 50 round boxes of Lapua 105grain loaded ammo, and we shot that, and that only. I experienced several instances of very hard bolt lift accompanied by extractor flow impressions and cratered primers. Not all rounds did this, only some. The rifle shot well (under 1/2 MOA for every group we shot with a best of .3 MOA).

We cleaned the bore after each round for the first ten rounds, then after every group of 3 for the rest. We ended up shooting about 30 rounds total, and the rifle performed great, except for these bigtime pressure signs from this Lapua factory ammo.

My theory is perhaps that the bullets were jamming in the lands, although I would sure be surprised if they were with a stock rifle and factory loaded ammo. I have a Hornady COAL gauge and the 6mmBR modified case, but the bullet comparator insert for my calipers won't arrive until next week. When it arrives I will make measurements on the chamber vs the COAL and ogive dimensions on these Lapua rounds.

Anyone else have any theories as to what would cause these high pressure signs?