I finished up the 6 tactical sergeants with combi-grav guns:
Fair play for tackling a fully-mechanised 5th Company project all in one go!
I started a similar project but only got as far as the purchasing stage (and painted just four marines... ), so I wish you all the best in your epic endeavour here.
It looks like you're off to a good start, but the picture above was something I wanted to mention; the combi gravs look pretty rough. I'm sorry to say that, because I appreciate how much work and money has gone into them, but the joins just don't look as good as your other work here. I'd be tempted to just use the newer-pattern combi grav bolters, or to add the grav nozzles to a Tigrus combi bolter. Anyway, not to be a negative critic or anything, I just wanted to make a suggestion that I think will improve the appearance of your efforts!