If you have access to an air compressor I would just buy the little spray kit. Duracoat is really easy to shoot but you want constant pressure going through the sprayer so you get a nice even coat. The aerosol kit may work if its just one gun but if you can, use the little hobby kit for $49.
I have used cerama-coat from Midway and it was pretty easy to use. I used it on a old Turkish Mauser barrel that I cut down and part's. A couple of light coats let it dry then bake in the oven. It has a strong smell when spraying but not when it is baked so it will not stink up the house. It is a nice flat black finnish.
I have used the Rem870 black duracoat on my remington 870, it's my hunting shotgun and I've used it and abused it for 3 years going on 4 and the thing still looks brand new. I just ordered a small batch of durafil to try out. If your going to go with a camo type pattern I would also buy a can of clear coat to even out the sheen of one color to the next. I use an air brush hooked up to an air compressor.