/vr/ - Retro Games

>>7723720
>>7724053
It doesn't have any specific name, no, and doesn't actually have any mechanical function, rather it's just a hollow metal cage (so to say) to cover the barrel and gas tube so that you don't touch them when they're hot (hence being referred to as a heat shield), also for giving a solid place to attach the ladder sight for the grenade launcher.
The underside of it is open, as the grenade launcher fits underneath it, and it's there because you can't mount the handguards on an M16A1 with the launcher.

It does look extremely aesthetically pleasing. As actual live 40mm M203 grenade launchers aren't widely available without some special paperwork (and getting 40mm loads which actually have explosive payloads is even harder than that), something that has been common has been mockups of various kinds, usually as 37mm flareguns, which you then fit with the classic heatshield, or a replica.
A year or so back, LMT, who has been making the M203 for a while, put out a limited edition run of M203s built as 37mm flareguns, just for the kind of people who want just that.