Absolutely!
These models of the Safariland Model 6360RDS ALS/SLS Mid-Ride Level III Retention Duty OWB Belt Holsters will most likely not work but the holsters at the link below should fit.
https://www.opticsplanet.com/safariland-model-6365rds-als-reg-sls-low-ride-level-iii-retention-trade-duty-hol.html?_iv_parent-gun-model=sig-sauer-m17&_iv_gun-model=sig-sauer-m17-1,sig-sauer-p320-rx-1,sig-sauer-p320-x-full
Yes, the correct model Safariland Model 6360rds ALS/SLS Mid-Ride Level III Retention Duty OWB Belt Holsters for you M&P are MPN:6360RDS-2222-131 (Right Hand), MPN:6360RDS-2222-132 (Left Hand), and MPN:6360RDS-8182-131 (Right Hand).
Yes, the Safariland Model 6360rds ALS/SLS Mid-Ride Level III Retention Duty OWB Belt Holsters that are compatible with the M&P (4.25" and 5"), are also compatible with the .40 S&W model M&P as well.
Unfortunately, Safariland does not offer a holster that is compatible with the FN 509 Tactical. I would recommend the Comp-Tac International Kydex w/Modular Mounts OWB Holster found using the following link:
https://www.opticsplanet.com/comp-tac-international-owb-kydex-holster-w-modular-mounts.html?_iv_gun-make=fn-herstal&_iv_gun-model=fn-509-tactical
This Safariland Model 6360rds ALS/SLS Mid-ride Level III Retention Duty OWB Belt Holster can fit Gen 1-4 Glock 17 models with suppressor height sights, but not with an optic equipped.
No it will not be compatible.
This is for the Glock 17, but the generation and MOS compatibility, is not given.
None of these options work for your firearm. Please contact us at techsales@opticsplanet.com for assistance
This holster will fit your P320 with optic and SureFire X300U on it.