[Deadeye]

Finally got to the local range for the second firing of my P380. Amazingly accurate at 7 yards for a DAO mouse gun. Using PMC FMJ I got numerous slide lockbacks, usually on about the third or fourth round. I did not experience any of these the first time I fired this gun, using Federal FMJ. When I got home I disassembled the pistol for cleaning, and did some checking. With the slide off I replaced the slide stop in the frame and loaded a round of Hornady Critical Defense into the magazine and observed as the bullet passed the nub of the slide stop which protrudes into the frame and is intended to be raised by the magazine follower to hold the slide open when the last round is fired. The conical ogive of this round cleared the slide stop nub by a considerable distance, and I'm guessing would not cause a premature lockback. I then tried a Remington FMJ round. The bullet's ogive just missed the slide stop, by about a thirty-second of an inch. I then tried a Remington Golden Sabre 103 gr. hollow point. The ogive of the bullet engaged the slide stop nub by a considerable amount, pushing the slide stop a considerable distance as it passed. Unfortunately, I had used all the PMC which had caused most of the lockbacks.
I have formed the theory that the bullet striking the slide stop nub as the rounds rise in the magazine is the cause of the malfunction. The fact that the malfunction does not occur every time leads me to theorize that there is a timing factor involved; not just that the bullet hits the slide stop protrusion, forcing it up, but also that exactly when in the firing cycle this occurs
is a factor. This is probably a matter of milliseconds. I'm guessing that though the PMC rounds may not impinge on the slide stop nub as much as the Golden Sabre, the shape of the ogive causes it to push the slide stop up at just the correct time to catch and lock the slide. I'm guessing also the magazine spring rate and follower design may be variables. I'll have to see if I can get some other various brands and types of ammo and check into this further. Ammo availability being what it is, this may not be easy.

 

[ron54]

Some ammo can cause the problems you are having. As these guns are shrunk down to subcompact size, tolerances become very tight and feed angles are steep, along with very stiff springs. So there are more chances that small variances in ammo or magazines can cause feed / eject problems and slide cycling issues. Limp wristing can come into play very easily as well. You might have to experiment with different ammo, paying close attention to bullet shape and length, as slight differences can affect reliability of cycling. I believe Kimber states for their solo to use certain specific brands and types of ammo, for the gun to function properly. Kahr does not, doesn't mean you a problem gun, just picky about its diet. Unfortunately in these times of scarce ammo it could be a challenge getting what works best easily.