I'm sure someone here has done the work.
Sig P365 and am wondering about loading 9mm for a short barrel ... 3" barrel.
low flash powder.
When moderator taliv requested information on low flash powder to use with night vision, I repeated my low light/night time muzzle flash testing using Night Owl XGenPro night vision scope.
Here's repost of my testing -
https://www.thehighroad.org/index.php?threads/need-low-flash-9mm-powder.809859/page-2#post-10357740
"Four loads were tested using Glock 22/KKM 40-9 conversion barrel (10 rounds of each load were fired):
HP-38 4.8 gr RMR 115 gr FMJ @ 1.130" - This load was used as reference and produced 4" long by 2" high orange colored muzzle flash from the side (Shooter's point of view - 1.5" round flash).
Promo 3.8-4.0 gr RMR 124 gr HM RN @ 1.150" - 1" long by 1" high faint orange colored muzzle flash (Shooter's POV - 0.5" round flash). In low light, muzzle flash was almost non-detectable.
BE-86 5.2 gr RMR 124 gr HM RN @ 1.150" - 2" long by 3" high bright orange muzzle flash (Shooter's POV - 3" round flash). This was by far the brightest muzzle flash of four powders tested.
CFE-Pistol 5.2 gr RMR 124 gr HM RN @ 1.150" - 1" long by 2" high orange colored muzzle flash (Shooter's POV - 2" round flash)."
Sig P365 ... 9mm ... 3" barrel.
Other than that, what would you like to do?
OP didn't specify whether full power defensive or lighter target load was needed but for general purpose range practice/plinking load, it's hard to beat Promo, especially cost per round.
I load for M&P Shield 9mm with 3.1" barrel, similar to OP's pistol.
Conventional reloading wisdom tells us faster burning powders produce more snappy felt recoil. Well ... then why do so many bullseye and action pistol match shooters use faster burning powders?
Reducing felt recoil yet producing accuracy can be done with faster burning powders.
With RMR 115 gr FMJ and 4.4-4.5 gr Promo loaded to 1.130" OAL out of Shield 9mm, this load produces felt recoil less than Winchester white box yet produces comparable level of accuracy (slightly larger groups) good enough for range practice and shooting drills (With 3" barrel shooting off hand, I don't think you could tell the difference) -
https://www.thehighroad.org/index.p...for-more-accurate-loads.841097/#post-10920001
With 4.1 - 4.2 gr Promo, felt recoil with Shield 9mm is a dream load to shoot. And if you want to squeeze out a little more accuracy, reduce OAL to 1.110".
I often take my coworkers and their families/neighbors shooting for defensive shooting training. Many of them have 9mm compacts and subcompacts like Glock 19/M&P Shield 9/Taurus G2 and I load RMR pulled 115/124 gr bullets for low cost practice (Plated bullets for pistol and jacketed bullets for 9mm AR carbines) but RMR in-house 115 gr FMJ with 4.4-4.5 gr and 4.1-4.2 gr Promo loads are standby loads I always keep in my range bags.
For accuracy testing reference, I use 115 gr FMJ with 4.8 gr of W231/HP-38/Sport Pistol loaded to 1.130".