five.five-six
Member
I have an M&P Compact 40 1.0 with a conversion barrel for 357 Sig and 9MM. I would not feel undergunned with any of them. That being said, the 357 Sig is snappier than 9. Have not chrono'd it yet, but there is a lot of "authority" to it. Reloading is a little different than a straight walled case, you really have to watch the belling and neck tension - just kiss the case mouth enough to alow the bullet to start. I also recommend the Lee FCD for good measure. Not all 9mm bullets are compatible with 357 Sig - they need enough bearing surface for the correct surface tension. Ammo is normally more expensive than 9 or 40, or was before Covid. I am still trying to find the best powder for my pistol, so no recommendations there at this time.
I’ve settled on AA#9 over 124 FMJs It’s flashy but it also not very dense which helps with the potential for bullet setback.
Brings be to another point, .357 sig is probably the most difficult round I load. With only .040 of neck, I was never really able to load is consistently without the lee factory crimp die. Less neck and a lot shorter to work with than rifle rounds. You have to use specific bullets with a truncated ogive and use every bid of OAL that will fit in your chamber and magazine. I’m still working up my load with AA#9 but my last string was about 1250 FPS with 12.4 AA#9 under a 124 FMJ FN.
As to: “it’s just a 9mm” “or “it’s just a small .40 S&W” . I have a pair of FS96, and I figured since I love this round, I’ll just get .357sig barrels for them. NO! You can find the barrels on GB and other places but beretta flat out says it will break the gun and confirmed by several internet stories of people who have tried it and have broken their frame.