EzGoingKev

I have the Midwest handguard and this is how I have a light mounted to it. It is a Surefire M640DF using a Arisaka mount to move it forward. There is hardly any shadow with the light there. My caveat is I have not run the gun with it mounted there so IDK if that is too far forward. Some medical issues and working on shortening a field stock for it have kept me from trying it out. That should give you an idea.

No M-Lok slots? IDK about that.

I could just barely fit 7 rounds of Federal LE133 in my gun. I replaced the OE magazine cap with one from Rx Arms. His cap has more internal space than the OE cap. Now I can fit 7 rounds with no problems.

I bought FFT's American made handguards and they did not just drop in. They needed work to fit correctly.

Are these stocks real solid wood or are they like a laminate type deal?

I am not sure if I am understanding you correctly. You want to buy one optic and swap it from your AR to your Benelli M4?

The first thing I would do is check with Benelli to see if they will sell you a replacement receiver. If they will not I would find a really good machinist that could make and install a custom insert to restore the threads.

Where are you located?