I have tried 407K, 507K, EPS Carry, SIG Romeo-X Compact, and Vortex Defender - these all fit the RMSc/modified RMSc footprint except when the slide has the 2 recoil lugs. Then only the EPS Carry (with its included plate), SIG Romeo-X Compact, and Vortex Defender can directly attach without an adapter.

The Vortex Defender before November 2023 was a 14 hour shut-off time and had a slow refresh rate. Vortex updated them and the one I just got (3 MOA dot) has a 10 minute 42 second shut off and the refresh rate is the same as any other dot.

The Romeo-X Compact is the only 99% American made RMSc optic. It's assembled in the US with 99% US made parts. From what SIG told me, the only Chinese parts are the circuit board and the mounting screws.

I wasn't a fan of the 407K 6MOA dot or the lens distortion with the 407/507. EPS Carry was crisp and clear like the SIG Romeo-X Compact. Vortex Defender lens is decent as well.