Upgrading to .40cal

[Bobster]

So, the longer chamber or "throat" of the 10mm still allows the .40 to sit in battery with correct head space? I thought on the rimless cartridges rested up where the lands/grooves start?

No, the .40 is being held in place by the extractor and in battery by the breach face. You fire the gun, the case expands in the 10mm chamber to hold itself in place while the powder burns and bullet goes out the muzzle. Pressure drops, bullet case contracts and is yanked out of the chamber by the extractor (usually). The .40 bullet travels about 1/4" before it hits rifling.

Rimless pistol rounds are usually located in the chamber (headspaced) by the mouth of the case. If you look in the chamber you'll see a small ring/ridge of where the case does this. If you take a .40 round and drop it in a 10mm chamber, it will go in deeper until it hits the 10mm ridge.

 

[Bongo Lewi]

LMFAO...I love how you CYA with the "I won't criticize" phrase amidst the 5 paragraphs of criticism.
if you like guns and shooting, you like guns and shooting. You can be a "range ninja" (whatever that is) and proficient with a multitude of calibers. The proposition that you need to limit the number of guns or calibers to be proficient is FALSE. No one cares what you shoot, but you.
if you like PRIVACY (fuck 4473s) and building things and geeking out with your tools, you "might" like building your own firearm and pretending to be a gunsmith (HAHA) However, of course not everyone is skilled enough to build a good "reliable" one, let alone shoot multiple calibers. Know YOUR limits, and stick to them. If someone wants to use a PMF for self defense, that's their God given right. smart or not.

I suggest not. Good luck with that.

 

[Bongo Lewi]

No, the .40 is being held in place by the extractor and in battery by the breach face. You fire the gun, the case expands in the 10mm chamber to hold itself in place while the powder burns and bullet goes out the muzzle. Pressure drops, bullet case contracts and is yanked out of the chamber by the extractor (usually). The .40 bullet travels about 1/4" before it hits rifling.

Rimless pistol rounds are usually located in the chamber (headspaced) by the mouth of the case. If you look in the chamber you'll see a small ring/ridge of where the case does this. If you take a .40 round and drop it in a 10mm chamber, it will go in deeper until it hits the 10mm ridge.

Firing 40 SW in a 10mm is not unheard of. Some do it because they have an appetite for being ridiculous. Or enjoy fucking with their jammed handgun at the firing line vs. shooting it. Bad idea with a carry gun though. The normal action is the round gets shoved out of the magazine and the extractor slips over the rim. This has to happen every time (duh). Since the 40 case is shorter it can go too far into the chamber. If the extractor doesnt keep it from doing so, it falls too far into the barrel. The firing pin cannot reach, so it will not go bang. Similarly, if the cartridge gets forward of the extractor yet does fire, it will not extract because the extractor dog is behind the rim.

Begs the question... why would you do this? It's exactly the same as loading 380 ACP in your 9mm. It makes no sense.

 

[bkbrno]

I shoot .40 in my ten on occasion because I have a metric shit ton of .40. It works fine but I wouldn't do it for defensive needs unless all I had was a 10mm pistol and .40 ammo. If that's the case, I know I can get a few shots off with some confidence. I don't do it a lot because I feel it stresses the extractor more than 10mm would.

Can't shoot .380 in a 9mm because it is straight walled and 9mm is tapered.