With the Kahr you don't need to rack the slide fully to reset the trigger. About 1/4" will do it and the snap cap doesn't eject.
Same with the Kel-Tek PF-9. Also, with the SKS, you don't have to retract the bolt all the way over the mag follower to cock it for dry-firing. I am sure there are a lot of arms for which this is true.
I use dummies or snap caps when I first try out an autoloader. Fill the mag with live rounds, three short of full, then a dummy, then two live rounds.
I started doing this when I bought an SKS with that rifle's known slam-fire tendencies, and since then have found two other guns I bought which give double-taps. One a brand new RIA .45, the other a used .22 pistol.
The full mag is to emulate the full magazine spring tension.
If the first two rounds go off with one trigger pull, then the dummy stops the phemonemon before an uncontrolled full mag goes downrange or upsky. And the dummy round wil be left in the chamber.
I try that a couple of times, then I just put two rounds in the mag to test it with low mag spring tension. (This is the most likely situation to produce slam fires, since the bolt or slide meets less resistance on closing.)
These are not positive tests for NON-slam firing, but if you do get slam fires it indicates that fixing is necessary. Beats getting a real surprise the first time you fire an autoloader with a mag completely full of live rounds.
I also use this procedure after doing any bubba-ing on the guts of an autoloader.
Sometimes I use reloaded (rebulleted only) empty cartridges for the dummies, and I magic-marker them green where the bullet meets the neck and in the extractor groove, where the color won't wear off, and sometimes I use regular commercial snap caps. Depends on whether I've got dies or not or money or not.
I've made snap caps by filling the dummy primer pockets with RTV and striking it off flush with any flat implement. Seems to work fine, but clean the primer pockets thoroughly first. Any adhesive's effectiveness depends on the tensile strength of what you're putting it on, and dirt doesn't have any tensile strength.
Yeah, I know, "check the gun before you fire it," but this is only sometimes possible, and a mere takedown and visual inspection may not reveal certain faults which can lead to slamfires.
