HUGE PROBLEM WITH BRASS IN MY RIFLE

Moderators: gds, bakerjw, renegade, bamachem

User avatar
dellet
Silent But Deadly
Posts: 6584
Joined: Fri Nov 30, 2012 1:25 pm

Re: HUGE PROBLEM WITH BRASS IN MY RIFLE

Post by dellet » Mon Oct 19, 2020 10:43 pm

If the subs aren’t sticking, it’s probably the bulge you found creating the hang up.

I would measure the base to datum length before and after the subs.

If you pull up a SAAMI drawing of the chamber it will sort itself out, but base to datum on the shoulder needs to be at least 1.071”. Less than that the neck can jam in the chamber and pinch the bullet with brass as short as 1.365”. There’s a lot of brass out there that comes from the factory less than 1.065” at the datum.

Minimum chamber should be 1.378” from bolt face to the leade into bore. Distance from where the shoulder contacts the chamber to the end of the chamber should be no less than 300”.

So you can see where brass with a short shoulder at 1.065, that is 1.365” long, uses every bit of that 300”, before it stretches when fired.

If you blow that shoulder forward with a light load, you probably won’t have to trim unless you want to.

The long case length is one of the reasons I like Norma brass.
300 Blackout, not just for sub-sonics.

BulletFlight for Android
Post Reply