Originally Posted by Tigger

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In one respect I agree with Ghost... On the other hand, I'm thinking the complete opposite. There's a chance the charge isn't burning hot enough to expand the casing to prevent blowback. If that's the case, you are actually in an under pressure situation. That could spell trouble if you rapid fire as you are now more likely to wind up with a round stuck in the chamber. Try to switch out ammo. If it still does it then I'd get the barrel chamber checked. Might not be perfectly cut.

If the barrel checks out then leave it with a gunsmith to diagnose. Any issue like that tells me there is a problem and no firearm should exhibit problems.