The FN 502 Tactical has mounting plates compatible with the Trijicon RMR footprint, Vortex Venom footprint, and Shield RMS footprint. The Holosun Holosun HE407K-GR X2 Red Dot Reflex Sight uses a modified Shield RMSc footprint. So the Holosun Holosun HE407K-GR X2 Red Dot Reflex Sight will not fit the FN 502 Tactical.
The Holosun HE407K-GR X2 Red Dot Reflex Sight uses a modified Shield RMSc footprint. If you have an HK VP9 optics ready model the plate listed below, which is Plate #4 might work. I would contact HK in regards to the plates compatibility with the modified footprint of the Holosun HE407K. If you do not have an optics ready model of the HK VP9 the other link below will take you to a compatible mounting plate. However, the rear lugs of the plate must be removed.
https://www.opticsplanet.com/heckler-koch-mounting-plate-1.html?_iv_code=13-RMT-MNTPLT1-50254264&_iv_fit=leupold-delta-point
https://www.opticsplanet.com/evolution-gun-works-leupold-deltapoint-pro-sight-mount-for-h-k-vp9-vp9sk-p30-p30.html
No, just like the other "K" models from Holosun, this one would also require slight modification to the slide indexing posts where the optic cut is to accommodate the 407K and 507K models from Holosun.
Yes, the Holosun HE407K-GR X2 6 Red Dot Reflex Sight will mount directly to the optic ready slide of your P365 FUSE without the need for an adapter plate.
The Holosun HE407K-GR X2 6 Red Dot Reflex Sight houses its battery on the side of the optic via a battery door. The optic does not need to be removed in order to replace it.
The Holosun HE407K-GR X2 6 Red Dot Reflex Sight is compatible with the G.U.M. Universal (Optics) Mount. The 407K will require (2) M3x8mm Flat screws, and (2) shallow mounting posts included with the optic mount.
The Holosun HE407K-GR is compatible with your Springfield Prodigy. You will first need to purchase and install the Springfield Armory HEX Wasp Agency Optic System Mounting Plate, which can be found linked below. With the plate installed, you will be able to directly fit the Holosun HE407K-GR to your Prodigy.
https://www.opticsplanet.com/springfield-armory-hex-wasp-agency-optic-system-mounting-plate.html
Yes. The Holosun HE407K-GR X2 6 Red Dot Reflex Sight will mount directly to any optic ready P365 (P365X, P365XL, P365 X-Macro etc.) without the need for an adapter plate.
The P320 M17 is designed to fit larger full size optics that use the Deltapoint Pro footprint. The Holosun HE407K will fit but will leave extra room on all sides of your optic cut. I would recommend using a larger Deltapoint Pro pattern optic such as the Sig Romeo 1 Pro, Sig Romeo-X Pro, Leupold Deltapoint Pro, Holosun SCS-320, and Eotech EFLX.
The Holosun HE407K is a micro-optic that uses the K/RMSc footprint while the M18 is designed to accept full size optics with the Deltapoint Pro footprint. While both this optic and a Deltapoint Pro footprint optic actually use the same pattern footprint, the Holosun 407K is much smaller and would not fill up the entirety of your optic cut. My recommendation is to use a larger optic with the Deltapoint footprint such as the Eotech EFLX, Leupold Deltapoint Pro, Sig Romeo 1 Pro, Sig Romeo-X Pro and more.