m305's blowing through primers

[mattcwc]

Hey, was out shooting and my buddy was shooting his m305's and his firing pin was blowing through the primers. He was shooting s&b ammo. Any one know why this is happening?

 

[yomomma]

First and foremost yo have to see if the firing pin has a dull round end. It may have lost a piece on the end and become sharp.

After that you need to know the headspace.

 

[45ACPKING]

First and foremost yo have to see if the firing pin has a dull round end. It may have lost a piece on the end and become sharp.

After that you need to know the headspace.

^^^^^ what he said

 

[mattcwc]

Ok thanks

 

[tiriaq]

Another thing - if the primer is losing a little disc, there is a posoibility that the blanked disc(s) could lodge in the firing pin hole, and cause the rifle to fire as the bolt closes.

The cause of the problem needs to be identified and remedied.
Does the firing pin tip fit the hole in the bolt properly?

 

[captainmike]

Understand it's s&b ammo but which bullet weight because I 've got the same problem with heavy bullet/slower powder in a semi auto and got some blown primer due to excessive gas and some primer went out of they pocket

 

[yomomma]

I shoot S&B with no issues. Sometimes with an oversized chamber the primer can back out when first struck. When the cartridge goes off it can push the case back against the firing pin causing a rupture. Somebody had a nice GIF to demonstrate.

 

[mattcwc]

My buddy's going to bring the rifle over this weekend I'll have to look at it all then.
Thanks.

 

[yomomma]

When you pull the trigger the firing pin pushes the case forward until the shoulder of the cartridge case contacts the shoulder of the chamber and then the cartridge goes bang. As the pressure builds the primer is forced out of the primer pocket back over the firing pin. If you bump the shoulder back too far this creates excess "head clearance" and how far to the rear the primer can move. Basically the firing pin hits the primer and then the primer is forced "back over" the firing pin which then acts like a cookie cutter and punches the center out of the primer that it just hit

This also applies to oversized chambers, like M305s normally have

 

[Oldsmobiler]

if you punched a primer I GUARANTEE the firing pin has a melted tip. Its like a blowtorch when lit off and it'll smoke a pin. Check it out ASAP