Is there any model of suppressor small enough in diameter to allow the use of a 40mm without removing the suppressor first?  I know its a wierd and out of the blue question but. I had an idea that I was contemplating.  I figured you guys would be the best place to ask.

I don't think there are, just going by photos.  You would have to use the short versons of the M203 or HK just to have room to screw on a can on the M4.  A full length M16 looks like it would have room to mount a can with a regular M203 mounted, however it also still looks like the suppressors do protrude into the bore path of the grenade, as well as the path of the 203 sliding open to load.

But I was wondering if something new had happend and someone might have recently built a launcher compatable suppressor, using a off center bore or perhaps using two smaller diameter chambers side by side with the bore running between them venting into them from the side, resulting in a unit with a flat top and bottom?

You would have to have an extremely large can to cause 40mm interference.

Thank you sir, thats what I needed to be sure.