Clarification on Rim Lock

Back to Kel-Tec stuff

The 32 is a semi-rimed case which means that the rim that the extractor pulls it out of the chamber with is slightly larger in diameter than the rest of the case. Most ammunition for semi auto pistols are not like this (such as the .45 and 9mm). In those there is a recess in the case before the rim, but the rim is the same diameter as the rest of the case so there is no way for them to be rim locked.

In the pic below you can see the 32acp 9mm and .45 laid on a flat surface. The 9mm and .45 lay perfectly flat, but the rim of the 32acp lifts the back of the cartridge slightly.

click to enlarge

In the p-32 (and probably most semi auto's) the ammo is slightly angled nose up in the mag like this:

click to enlarge

This will keep rim lock from occurring if the width of the mag is not much more than the over all width of the ammunition. This is because the angle keeps the top of the rim on the bottom cartridge (A) pulled back and the rim on the bottom of the top cartridge (B) pushed forward like this (exaggerated):

click to enlarge

But if you throw in a shorter over all cartridge (ie hollow points) then they are able to move more forward and back in the mag which could allow the bottom of the top rim to get behind the top of the bottom rim like this (The top round would be rim locked if this were to occur in the mag):

click to enlarge

If this were to happen in a situation when you needed the weapon your best bet is to drop the mag and insert another because you will not clear it by racking the slide....

Some believe that if a rim lock has not occurred when you are done loading the mag it will not occur (That bouncing around in your pocket is not enough to cause rim lock because the mag spring is enough to keep them situated once loaded, although others say they have experienced it on a carefully loaded mag). Loading is when you are pushing on the nose of the top bullet to get the next one in, and that will separate the rim of that one and the one below it, and could allow them to get into a rim lock situation. Like this:

click to enlarge

So they say to make sure each round is pushed all the way back and to load carefully and look for rim lock (look down the front of the mag for one that slide forward more than the rest) after you finish loading, and if you carry with a full mag + 1, chamber the +1 with another mag, not your carry mag then put another back in (because after stripping the first round the lower ones could have moved around and loading after that can cause rim lock).

One fix for this is to take the mag apart and make a plastic spacer to put in the rear of the mag (this also requires shortening the follower to accommodate the spacer) to shorten the inside dimensions of it so that the shorter ammunition can not move enough forward and back to become rim locked. But this makes that mag a HP only mag and will no longer accept FMJ.

Now there is an easy answer if you want to use HP's, the Flyer Wire is a small wire spacer that solves the problem.

My personal opinion is to carry FMJ in my p-32. This is because of the better penetration of the FMJ and it being more likely to get to something vital. That and looking at how many of the HP's that did not expand, or only expanded a little (look here) was not worth the trade off in penetration and reliability of FMJ's to me. That you must decide for yourself. Here are some pro's and Con's of FMJ vs HP's on 32ACP