Wow, it's been a minute. I do recall that the spring clip thingie went behind the A1 flash hider, and I don't see why it wouldn't have worked as well with the A2 flash. Beyond that, the launcher was a deal that slipped down over the muzzle/flash/spring, and then you put a grenade in that, and then there was some kind of band you wrapped around the grenade spoon, and then you pulled the pin and launched. IIRC the shock of launching dislodged the retaining band, and the spoon flew off, and then the whole mess exploded downrange (hopefully).
I hope this is right. It's been almost 50 years, and we only trained on them for one day, and only with smoke grenades. Someone else might have better information.