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+--- Thread: 10mm vs .40 S&W (/Thread-10mm-vs-40-S-W)
10mm vs .40 S&W - srjdsmith - 09-19-2026
Boys and girls, it’s time for the naive question of the day:
Recently I heard that .40 S&W ammo can be safely fired in a gun chambered for 10 mm. (The way 38 spcl can be fired in a .357 mag weapon.) Now, I was already aware that the bullets are the ‘same’ diameter, but it never occurred to me that you can shoot .40 out of a 10mm.
Before you get all worried about me, I don’t have any .40 ammo and if I was to do something like this, I would load 10mm on the ‘light’ side using a published, approved load (probably from Hornady 12 ed like the 155gr at 1150 fps).
This is a philosophical question, not a practical question. My son and I have P80 G20 clones and I purchase and load 10 mm for whitetail deer hunting for them. They’re very effective. I have no reason to shoot .40, but as intellectual curiosity, is it a thing?
RE: 10mm vs .40 S&W - olfart - 09-19-2026
Basically, 40 is 10mm short.
RE: 10mm vs .40 S&W - tommag - 09-19-2026
It could be, but you'd need a strong extractor to hold the case since they headspace on the mouth. In a revolver chambered in 10mm (do they make any?) It would be very doable with moon or half moon clips.