we have 2 types over hear
no 1 we call a can that goes from the end of the barrel out
a is fixed on by a 1/2" unf x 20 TPI thread on the end of barrel.
no 2 is a 2 point mounting system where the moderator fits as above but from the baffles back the moderator then comes back down the barrel toward the stock.
this makes for a stronger mounting system and lets gasses come back down the barrel(not on the barrel as there is a internal tube to encapsulate the gasses)this is meant to make them more efficiant.(please correct me if i am wrong)
sorry but hear is a every crude picture,
again sorry bet it is the best i can do