Background first. This year The Boss bought me a 12 F-Class in 6BR in lieu of a Christmas bonus. (Yeah, he actually did and no, we're not still hiring )

I topped it with a Sightron 8-32x56 that I had on hand and ordered the components to start loading. Everybody said to buy Lapua brass but I couldn't find any--out of stock everywhere. Norma brass was actually cheaper ($93/100 at Midway) and available so I bought 200 pieces.

I loaded some ladders with RL-15, 8208, and Varget with 105gr Hornady BTHP's and CCI450 primers starting 0.015" into the lands as measured with a Hornady gauge and a piece of new brass that I drilled and tapped myself. Shot the RL-15's first starting at 27gr. That's a fairly light load. Quickload predicted ~2680fps at 47,500psi using a start pressure of 7200. Actual velocity was only 2580 but it must have randomly landed on a low node as it was wicked accurate. After sighting in my first 3-shot group went 0.159".

Nothing I have shot in 4 sessions with this gun has grouped larger than 0.43". The best was with 28gr of 8208xbr--2826fps and a 5-shot group measuring 0.136". Really could have been one round hole but I was giggling on the last shot and it screwed up my breathing sending one a bit high. So, out-of-the-box this rifle is abso-friggin-lutely brilliant. Except...

It craters the crap out of primers on every load. And I mean BIG craters. Didn't actually pierce one in 100 rounds, but they're just a bug's breath shy of piercing. About 20% of the craters were so pronounced that I had to grind them off to get the fired case to fit in a Redding shellholder. None of the primers had backed out and none were flattened at all with any load.

So I researched. Common problem with Savages. Firing pin hole, firing pin tip profile, headspace--got it. So, have the firing pin hole bushed, re-profile the pin tip or try a PTG bolt head. Well, I had a PTG bolt head on hand for another project. Very reluctant to change anything on this gun but I just wasn't comfortable with those craters.

Now the PTG bolt head is considerably shorter than the factory bolt head when measured from the back of locking lug to the bolt face--about 0.0125". I ordered a PTG go gauge so I could re-set the headspace.

Then I took some measurements with a Hornady comparator and a 0.375 headspace bushing. Brand new Norma brass is 1.138"-1.140". The PTG go gauge is 1.141". My fired cases all measure 1.145".

I had a hard time finding any official headspace specs from CIP. I did find a reamer print from Kiff labeled " 6mm BR Norma (CIP) European Standard" that shows 1.1453" minimum to a 0.375 datum line. In fact, all of Kiff's 6BR reamer prints show this same value.

It looks like the factory headspace was correct based on the fired cases, but new cases are a bit short resulting in high-normal to slightly excessive headspace on first firing. Can't explain why the go-gauge is so short.

So what's the best thing to do here?
Reset the headspace with the go-gauge and bump the shoulders on my fired brass? Reset the headspace on a fired case, let the brass stretch and hope the new bolt head solves the crating issue? Any other suggestions?