Okay, I know that 10mm revolvers use moon clips, and by extension you could fire .40S&W out of 10mm revolvers using those moon clips.

By extension, couldn't you also shoot .357SIG out of 10mm revolvers using moon clips? Would there be a reason to (or not to)? I realize that the bullet won't fill the chamber - is that a problem?

I don't know why this came to mind, but it did.

I'd imagine some accuracy issues, with the bullet not being fit to the barrel/rifling.

Horrible accuracy, and I would expect the case mouths to split because they wouldn't be supported by the chamber.

Don't do that. It will fire, but point of impact will be completely unpredictable, and you may rupture a case. I've seen 9mm fired out of a .40, and while it did fire, the brass looked pretty funky and bullet impacts on target were keyholed all over the place.

I thought it was strange when it entered my mind. I didn't consider the case mouth thing at all, but I knew the accuracy would be really off.

In my mind I imagined it ping-ponging down the barrel, which I knew wouldn't be good, ha ha!

Sure, for giggles, on in a life or death situation (up close, because you will have very low pressure and very low velocity), or maybe as the plot twist in a bad murder mystery novel.


Wish I had one to try, I'd love to see the velocity loss. My 10mm revolver won't take full moon clips...

357 SIG cartridges fired in 40 S&W chamber:



I believe something similar would happen if a 357 SIG cartridge were fired in a 10mm Auto pistol which I believe would be possible because the extractor would hold the cartridge in position to be struck by the firing pin.

Yep. What people overlook when doing things like that, same with shooting 40S&W in a 10mm is tolerances vary, headspace can be all over the map. In one gun it's a non event, in another it's blown out primers. A practice best avoided.

Please don't. I don't know about long term effects. When we switched to 357 back in 2008, a bunch of us still had our .40 cal off duty guns and someone was firing 357 out of his Glock 23. After a few shots, I could hear it sounded different and stopped him.

His shots were all over the target.

But we did seize a Glock 31 off some idiot last month and he had it loaded with 9mm. I didn't bother asking him if he'd shot it that way.

Keep in mind that I was referring to revolvers with moon clips, not semi-autos.

No, don’t do that. The 10mm is .40 caliber. The 357Sig is .357, so firing one in a 40 cal barrel will go off, but the accuracy will be abysmal.

Like idiots who shoot 9mm in a 40

In a revolver, I’d be more concerned about way more powder burning between the cylinder and the forcing cone. Big flash, burning powder flying all about, and a projectile not hitting the forcing cone dead center as it would when the proper ammo is used. It cannot be good for the weapon or the shooter.