Board Thread:Warhammer 40k General Discussion/@comment-211.26.90.25-20130827133032/@comment-124.177.48.23-20131125085752

Like I say, have you tried the Ultramarines Omnibus? It quite clearly states that the standard Astartes bolter fire a .998 calibre shell. It is also mentioned in the codex(5th, I believe). And yes, the bolter is similar to an RPG.

However, I reiterate that only Imperial Guard use .75 calibre weapons, because their sub-Astartes form cannot cope with the recoil from a full-sized bolt weapon, whereas a Astartes is quite capable of picking up a heavy bolter or even a lascannon and firing it. And have you played Space Marine, a canon game? It mentions when you aquire the bolter that it fire a .998 calibre mass-reactive shell.