Hey bud,
The 620LT is for Remington semi-auto shotguns right? I have the 618 for my 870 that has the pressure pad, and then the momentary/constant-on switch.
If your concern primarily disabling for storage, or to prevent unintentional white-light activation while in use?
There are Surefire forends that have one or both rocker switches, the constant-on / momentary, and the momentary / lock-out. It's theoretically possible in terms of cracking the thing open and re-wiring it. The constant-on bypasses the momentary pressure switch to go fully on. You would need to wire the momentary and essentially put the rocker switch in-line with the momentarty so when you flip the rocker off, it won't go on. That being said, I personally wouldn't feel comfortable doing that. Those forends don't come apart that easy and I'd be hesitant to crack something open already configured and possibly potted for recoil and heavy usage and potentially compromising reliability and voiding warranty repair.
There's a couple things you can do...
- Trade your unit for one that has the lock-out switch.
- There's a switch cover for the pressure switch, essentially a stick-on piece of trimmable metal that covers all but the desired part of it you want to press to make accidental activation less likely.
- Use a flip-down beam cover to cover the light to avoid white-light ND's.
- Partially unscrew the head to prevent it from coming on during storage.
That's all I can think of. Good luck!