I had one of the Cobray 37mm flare launchers & original M203 handguard w/leaf sight & carry handle mounted M203 quadrant sight so figured I'd put'em on to see what it looked like, it's an "approximation" of an M203 mounting at best, the launcher sits much lower than the M203 & the rifle is very unweildy & uncomfortable w/the flare launcher mounted, difficult to handle & even carry, the quadrant sight even makes the carry handle difficult to use!

May try an airsoft M203 launcher, there seems to be a number of them that are very detailed copies (at least cosmetically) of the actual M203.

A detail pic of the original M203 carry handle mounted M203 quadrant sight.

That poor, poor rifle. Put some A2 handguards on it, and that's a rifle I'd want to have...

I don't have any experience with this, but I'm just wondering... Should the mounting bracket be hanging down that low? Is there some widget where you attach to the barrel that you could adjust or turn around to get the  mounting bracket up under the handguard?

ETA: That looks like a sling mount on the left side of the handguard, by the way...

hahaha, shade, exactly my feeling, I was going thru boxes, found the launcher (forgot I even had it) & figured I'd see how it looked, it's already back in the "proper" configuration for what it was built to be, a late 80's early 90's rearsenaled A1, which as far as I've been able to ascertain should be w/the triangle A1 guards as shown, although the round A2 guards is an interesting idea, anyone know if round A2 guards were ever fitted to A1's when they were rearsenaled? The purpose behind the late rebuild A1 was to have a rifle w/the later items that weren't used in VN (I have 70-71 era A1 built to VN era configuration), the late A1 shown has the replacement A1 upper w/cartridge deflector, front & rear night sights, the lg round forward assist etc & I was hoping to be able to "display" it on the M16 "wall" w/a representation of the M203, handguard & sights, but that isn't going to work w/the flare launcher LOL!

Mark, no way I can see to raise the mounting w/o some metal work (which wouldn't be worth it in my opinion), the flare launcher actually uses mounts that are very similiar to real 203 mounts, the back mount is a ring on a block, it slips over the barrel then slides into the barrel nut w/a pin that holds it in place, the front mount is the same but is in 2 pieces for the barrel, you put the mounts on the barrel then the launcher has a square cutout it's full length on the top, the bases on the mounts are cut to fit into the cutout, then you line the mounts up w/side to side holes on the launcher & put a pin thru the front & back mounts to attach, you can see the cotter pin that holds the pin in place in 1 of the pics, so it's pretty much a 1 way mount, the problem w/the "angle" the launcher sits at is the front mount for the launcher seems to be made for a HB, I used aluminum blocks to shim it to fit & didn't get'em lined up right, I guess if it's on a HB barrel it would at least sit straight, oh well, it was something to do for an hour or so hahaha.

I don't see how anybody was able to lug that clunky-ass thing around a battlefield.

I have seen pix of M16A1s with round handguards in the hands of troops in Iraq/Afg.  IIRC they were either Airforce or NG troops.  May have been dirt Navy (SeaBees)???.  Not sure they were all 100% A1, could have been rebarreled with A2 barrels also.  In a few of the pix IIRC not all the rifles were outfitted with the round A2 guards, some still had triangle guards which would seem to indicate they were just repaired at a lower level with current inventory replacements as needed & not a total rearsenal.

Yes, it sucks to carry that beast. I hated it and found I'd rather carry an M249 over that.

But...what the OP has is pretty cool.

I was issued a M-16A1 with A2 style handguards in an NG Mech infantry battalion in 1993. Rifle was a sweet shooter and an A1 in every aspect except for the handguards.