I really wonder why there's been such a rule. Space Marines can't carry the assault cannon, but they can carry the Heavy Bolter. Which is, in my humble opinion, just as heavy, and should suffer from about the same recoil problems.
And why should a Space Marine in power armour be acle to effortlessly lift a truck (Warriors of Ultramar by Graham McNeill), but not weild such a weapon? Why can Terminators fire the assault cannon even when moving, but swing a power fist no faster than an unarmoured human?
Okay. Nerd's thoughts. But I think I might start a conversion based on your sketch.
I just started to ask myself why a Terminator can't carry a Heavy Bolter 0.o Well, I guess we'll just have to get over the fact that 40K is very patchy. If you start a discussio about these things you'll never get to an end.
True. Try to ask such a question in a fan forum, and the answers you'll get will be 10 % "this thread is useless", 10 % "because.", 20 % "I always wondered why", 20 % "it's been discussed like 40,000 times before, so shut up" and 20 % "they'd look stupid".
Some of the gamers I know are almost fluff nazis - and as much as I love to discuss the fantastic 40k background, this is a serious problem to my mind - it's a game, after all, taking place in a fictional universe, where anything is possible. So that's why I think "why not? Doesn't hurt anyone".
Maybe we'll once see a power-armoured Space Marine with an assault cannon - who knows? Five years ago nobody thought of a Land Raider with Assault cannons and heavy flame throwers.
Gatling Laser? Good idea! I actually think its calles a multi-laser in 40k, but thats unimportant. Thats a very good piece of 40k art. Say, could you make a Space Marine with a Fallout 3-ish or C&C railgun?