Ok, i have a player with a Devastator character that wants to arm mount a heavy bolter. According to the arm mounting rules it doesn't say anything about a limit on size of weapon. I am having a hard time justifying this as I have never seen any pictures are whatnot with a SM having a heavy weapon arm mounted. What he ultimately wants to do is arm mount 2 heavy weapons (one on each arm). Help me give a reasonable excuse to say no to this (as he already decimates thigns with one HB). I know as GM I can just say no, but I feel I need a rule backed excuse to deny his request.
Also, I have a Techmarine player that wants to mount heavy weapons on his servo arms, again I have not seen anything other than the new techmarine mini (Thunderfire cannon) to support this being able to be done. Also, I find no rules to support what he would need to do (talents and whatnot) to be able to do this if it can be done.
Thanks in advance.