[honestbroker]

I have a Ruger 10/22 with a 20" bull barrell. This is a rifle I have put together from after market parts and only the trigger group, magazine and bolt with Volquartsen extractor and firing pin are Ruger. I have had this rifle only a short period of time. My Problem is my Armscor .22LR ammo is, with some regularity, blowing out the back of the cartridge case into the action and blows out the magazine. I am also getting approximately a 3 round burst instead of a single shot. Most of the time the rifle works properly and with very accurate shooting to 100 yards. I am wondering if the problem is with my bull barrel not having a big enough chamber for the cartridge causing it not to fully enter the chamber on occasion and the bolt hitting the primer setting off the cartridge with it partially out of the chamber? This might explain the multiple round burst. The rifle was completely cleaned before usage.

 

[MikeG]

"Cartridge blowout" or rupture of the case is likely caused by (no particular order) 1) defective case, 2) gun firing out of battery, or 3) lack of support in the chamber. Probably firing out of battery, unless the chamber was just really, really oversized.

A 10/22 doesn't "lock up" so yes, it could be firing with the bolt not far forward enough.

It could also be unlocking too early, especially if someone lightened the mainspring.

Take the barrel off and see if cartridges drop freely into the chamber. If not... there's a serious problem.

3 round 'burst' means the trigger group isn't functioning right. Too light of a trigger return spring? Fix issue #1 and see if that problem goes away. They could be related.

Good luck....

 

[JBelk]

You have multiple problems that are dangerous. Could I recommend a visit to an actual gunsmith?

 

[Darkker]

Sounds like a FCG problem to me. But if you had a tight Bentz-type chamber, and the cartridges were within spec, but longer like a stinger; there is the issue with the chambering.
Still have an underlying issue with the FCG.