Case head separation with new Browning X- bolt 300 win mag.

[huntinfool18]

That's within spec. Shouldnt be giving you a problem

 

[Hugnot]

Headspace at the shoulder. Having an exact or real close headspace measurement taken at the bolt face between belt & shoulder is unlikely. Ignore the belt, a useless feature put on certain cartridges & retained only because some shooters think the belt is needed with cartridges having a shoulder.

A .458WM should have a belt. There is no such thing as a .47-70 rimless.

"I took the rifle to a gunsmith today who checked the head spacing with go- no go gauges and said the spacing was good." The chamber might be within specs. Repeated F/L sizing driving the shoulder back at each sizing will result in a case separation just forward of the web.

F/L size at the shoulder & forget about the belt. Getting a 6.5mm, 7mm, or .30 PRC is an option (no belt).

The 1976 Wimbledon match having a score of 299-21X was won using a .300WM head spaced at the shoulder. A shoulder based headspace would have more precise control vs belt length that might vary a few thou inch from cartridge to cartridge.

Anneal the brass to reduce spring back & head space on shoulder. I use a .007 feeler gauge between bottom of F/L die & top of shell holder that assures consistent shoulder-based headspace.

Browning ain't (is not) going to say the chamber is screwed up. There is an option of buying "long" brass.

 

[jammer300]

Just an update. I talked with Browning yesterday about my rifle and was told that a gunsmith at Browning inspected the rifle and found it to have a rough chamber. After polishing the chamber and checking headspace they test fired it and had no issues with the test firing and the brass looked fine. I was able to shoot it this morning and did not have any problems or signs of case head separation so it looks like polishing the chamber may have fixed the issue.