[stoble]

I read about how single-column magazines can have a problem called rim lock. The specific cal. discussed was 9mm and 40 cal. I am not familiar with rim lock. What is this problem and can it happen in all semi auto calibers? Thanks guys!

 

[CharlesRiverCobb]

It's where the rims of the cartridges get snagged on each other within the magazine, or - I guess - while feeding. I read that it is prevalent with "semi-rimmed" cartridges like .32 ACP, but it sounds like it is possible with "rimless" cartridges like 9mm & .40 S&W.

 

[GonzoGeezer]

And it is definitely an issue with .22s.

 

[stoble]

So I assume they get locked up and bullet feeding stops. This seems so unlikely since the spring is pushing upward, the mag's inside surface is smooth, and the brass is very smooth. I wonder if some other error adds to this happening in a mag? Is the fix to jam the rounds down to unlock the rims?

{Plus 1 for revolvers}

 

[wsteinborn]

.22s and .32s
Never heard of it on rimless cartridges.

It is where the rim of the top cartridge is trapped behind the rim of the cartridge below it.

I had it happen, once, in a .32ACP. Never in a .22

Only happens when you use cartridges significantly shorter than the magazine was designed to hold. Like .32ACP hollowpoints