SIG Romeo MSR Gen 1 Optic Protector

After trying rail mounted optic protectors and having them break constantly, I decided to make a mount for the front of my Sig Romeo MSR to attach a 6mm thick, 29mm diameter polycarbonate lense. This lens was custom cut, so I don't expect that it is available for purchase online but I have not looked myself. I purchased a large sheet of 6mm polycarbonate off Amazon to cut my own lens protectors from. The assembly consists of the following parts:

• Lens clamp

• Polycarbonate lens protector (6mm thick, 29mm diameter)

• printed gasket (0.6mm thick)

• 8mm long m3 cap head screw

• m3 nylon lock nut (normal m3 nut will also work)

Notes for printing and assembly:

Replaces front flip-up lens cover.

This lens protector is designed to specifically fit the Sig Romeo MSR Gen 1 optic, and will not work on the newer Gen 2 Romeo MSR.

I printed the main clamp part with Fusion Filaments HTPLA+, and printed the gasket with ninjaflex edge TPU, however any TPU will work. The gasket does not need to be TPU, but this will ensure a good seal to prevent dust from getting between the lens of the optic and the polycarbonate protector. Be sure to assemble the optic protector with the gasket between the body of the optic and the lens.

THIS SEAL IS NOT WATERPROOF, and is only meant to keep dust out of the optic. So far it has done a decent job of keeping dust out, and you can experiement with adjusting the thickness of the gasket to get a better seal.

The Polycarbonate lens was cut using a bandsaw, and then finished with an oscillating spindle sander. I put tape on the top and bottom of the polycarbonate before cutting, to prevent scratches to the lens. The tape was also used to trace a circle pattern with the included cutting jig before being cut. The cutting jig is 28mm in diameter so that I could cut around the outside of the traced line, and then the lens protector was sanded down to size with the spindle sander. The lens does not need to be perfectly round, as the lens clamp has a lip that covers the edges.

I used a nylon lock nut to ensure the screw would not back out while being used on a Tokyo Marui MWS. The clamp itself will still hold on to the optic even if there is no screw, but the screw ensures the clamp will not fall off.

The model for the front tube of the Romeo MSR is included so that you can make your own optic protector if you so choose. Or, use it as a base to design protectors for other optics.