bolters design: It's too outdated looking, I'd prefer it to be bigger and look a little more hefty, it looks like an mp5 in size comparison on a Space Marine. Also it needs a stock. You shoot a rifle without a stock and tell me how accurate you are.
I do prefer the post, what was it, 2000? 2005? Where they introduced the slimmer, taller Bolter. The thing is the Bolter used to have a stock on the old weapon sprues. And there is plenty of artwork depicting stocks on Bolters. I do think with the increased strength and bones of a Marine, coupled with the power armour they probably don't NEED stocks. Also SM's are meant to be shock troops, up close and personal, tearing the guts out of the enemy army. I don't think you need a stock to place accurate body shots on an enemy at 30m when you're a 2m tall power armour wearing superhuman.
I so agree with calling BS on Marine loss rates. While you will always lose some in combat it should be more akin to fighting the blind school. I agree the enemies of the Imperium are also good, but if an IG army doesn't get wiped out to a man in seconds then against the same enemies a squad of SM should stomp all over them. In the fluff universe there are too many things that can kill a Marine too easily. Heck Cain, Gaunt and Eisenhorn knock off traitor Marines with little difficulty. I know the idea is to put the hero faction above the others in a story but I just read a Cain novel where a Genestealer kills a Terminator in about 3 seconds, while Cain fights them hand to hand for ages. Really?
I don't understand a Tyranid invasion. Surely all that is needed is some mycetic spores? Like a virus bomb that melts an entire world into goop (and then ignites it, true). Goop a world, suck it up, move on. No invasion, no chance of losing.
And MISSING WITH A LASGUN. WTH? HOW? Really if you can see it, you should be able to hit it. No windage, no bullet drop, no recoil, no nothing that makes shooting hard. The only two possible issues I can see are 1) the beam may take some time to burn through the target, even if it is one or two micro seconds then keeping it on target to do damage could be a problem, 2) beam attenuation in a debris filled war zone.