Very interested in this. When it was first announced I posted in some early thread that it sounded stupid/useless and had a few people point out that the reduced recoil could be a significant benefit for some. Since then, I've watched my mom struggle to handle SD loads out of a 9mm 365. May need to grab one of these and ship it up to her.
Thanks for putting it to the test.
Weight of slide is a factor in reducing slide velocity. Wouldn't the 9mm slide be heavier than the 380's slide? If I missed weight comparison, then I apologize for the post. My .45 ACP Shield's side had serrations on the underside to retard velocity.
A most infesting thread, Mr. OP.
Hello, the 9mm slide is ~2.5 oz heavier than the 380.
Slide velocity between the two is difficult to meaningfully compare because the power of the caliber is different.
So even if the velocity of the slides are the same, the power of the cartridge that the spring and slide (and shooter) have to buffer is very different. That’s what drives the difference in felt recoil.
Basically if you get hit by a bicycle rather than a motorcycle, even if they’re both going the same speed….
@JCN - thanks for doing all of this...and I hate you for doing all this. I'd just about decided I didn't need to pay attention to these and now it might be the answer to my issues (hand issues - nerve/ligaments).
Are there any differences to the slides between the .380 and 9mm? I know SIG's site says they're suppoed to be the same but...I'm curious if the .380 will fit in the Aholster pocket holster for the 9mm.
@alohadoug
External slide dimensions are the same.
Optic cut is forward compared to an X/XL so holster interference there can be an issue, but heat gun +/- Dremel solves a lot of holster issues….
Pardon me for bumping this thread. I’m late to the .380 club; having just recently assembled a P365-380 to help my wife ease into the P365 game. I’ve already spent more money on ammo than the gun!
I guess it’s common knowledge by now; the top of the .380 slide is ever-slightly lower than the 9mm P365 by about 2mm. So, the .380 may rattle around in hard P365 holsters. You can see the gap between the top of the slide and the holster in the pic below:
This also means the optic cut is shallower than the regular P365 so red dots are unlikely to co-witness with the factory-height sights.
The regular P365-380 comes with older-style Siglite three-dot nightsights. Mine had #8 front with #6 rear. I replaced them with Xray3 SOX10007. For me, the .380 POI is higher than the 9mm using same sight picture. Where the 9mm impacts at the dot (combat sight picture?), the .380 impacts at the too of front sight (center hold?). Some of the newer special edition P365-380 (Rainbow, Rose, etc.) now come with Xray3 sights.
Finally, I’ve had great luck shooting PMC 90gr FMJ and 1776 75gr Lead-free ammo but Hornady Critical Defense 90gr simply won’t feed in this gun. I’m kind of peeved since I bought a case of the stuff.
Hornady Critical Defense 90gr .380 failure to feed every two to three rounds with Sig factory .380 magazines.
Last edited by crosseyedshooter; 03-02-2023 at 11:39 AM.