Inverted primer strikes

[brokeasajoke]

A friend called me last night and asked me about a problem with fired primers on a Bear Creek Arsenal 10mm rifle. The primer strikes are inverted. He changed the trigger and sent it back because of this without taking his new trigger out. The rifle came back saying the trigger was the problem. My thoughts was it is a weak firing pin spring or hammer spring as I'm not sure the system used on these. Familiar with the AR-15 floating firing pin but not a pistol caliber BCG. Thoughts? I guess mostly is the safety aspect of it in being safe to continue or not.

 

[shoot4fun]

OVER PRESSURE!!!!!!!!!

 

[Propbndr]

Ditto what Shoot4fun said. Is that reloaded ammo? It looks like a type of primer crimp I have seen on some military brass.

 

[brokeasajoke]

No this is absolutely not reloaded ammo and does this with multiple types.

 

[Jon Leary]

It is caused by too large of a hole in the bolt

 

[rwj]

It is caused by too large of a hole in the bolt

… combined with sufficient pressure.

 

[gunsandgunsmithing]

It is caused by too large of a hole in the bolt

… combined with sufficient pressure.

...and other factors. One is fp spring pressure. Another is fp tip shape/condition. The fp tip diameter is another one. A bigger tip stretches, displaces and weakens more brass/area of the primer. Several factors but actually, pressure is pretty low down the list of causes. It's not a pressure sign by itself.

 

[brokeasajoke]

Maybe something in the gun is causing pressure. Maybe bullet setback as the round enters the chamber but it is factory ammo.

 

[shoot4fun]

No this is absolutely not reloaded ammo and does this with multiple types.

Most 10MM, as most all the firearms chambered for it are relatively recent manufacture and of sufficient strength to handle maximum SAAMI pressure. That said, it has been my experience that many of the 10MM factory offerings are, shall we say, loaded stout.
This I have found is especially true with European headstamps (they generally load ammo hotter anyway).
I do agree with @Jon Leary and @rwj that there is likely something not quite up to par on the firearm as well.
After all, it is BEAR CREEK and that is not top shelf for sure. I've read of many issues of all types with BCA parts.

 

[243winxb]

Bear Creek Arsenal 10mm rifle.

This type of rifle may be the blow back action type?
There is *no delay on firing. No delay may allow the action to open while pressure is still high. May see fake pressure signs, like the primer photo.

The weight of the bolt carries is made a lot heavier to slow the action at firing.

*Not the safest type of action. IMO. Best if action is a Delayed Blowback

 

[jelenko]

BEAR CREEK and that is not top shelf

Yeah.