[Skruface]

Okey dokie folkies,

I have a TM M733 that I am trying to "update". :hammer:

I have swapped the upper reciever for an M4A1 flat-top, and have installed a G&G M733 1-piece outer barrel and Nitro top rail. The problem I am having is mounting the TM RIS I have.

It seems like the RIS is not long enough. The Delta ring does not hold the bottom "panel" of the RIS tight enough to stop it from falling off at the slightest touch of the D-ring. Or, maybe it's the collar for the handguard that's attached to the front sight that's too short to hold the panel in place.

I suspect that the problem is the outer barrel - I think that the front sight placement on the M733 barrel might be farther from the D-ring on the 733 than on the M4A1, creating the extra space that allows the bottom panel of the RIS to fall out. I also found (during my research) a comment that the M733 handguard was marginally longer than the M4A1, further supporting this theory. I do not have an M4 outer barrel on hand to compare/measure, though.

Does anyone have an outer barrel from both an M4A1 and an M733 that could measure the distance between the D-ring and the front sight for me? If they are different, the problem is solved. If they are the same, then the issue is the D-ring and/or front collar, and the problem is still solved.

Any help is appreciated.