If your not real sure, try Testors Military Flats first. They can be completely removed with a little work (Gun Scrubber, Hoppe's, etc) and you can get them in pretty much any color needed to match your desired pattern or any you chose to make up. They also make it very easy to touch up if you want to.
Alum Hyde II is more of a "semi" permanent paint. Its great stuff, but it wont come off easy. I've used it as a base for camo jobs on a number of guns and painted everything from guns, stocks, scopes, knives, even a bike, with it. It holds up very well to abuse and solvents dont seem to bother it.
Just a suggestion for your camo job. Degrease well and plan it out ahead of time on how you plan to paint and how your going to hang everything to dry, and have it all set up before you start.
Use the lightest color in your pattern as the base and spray it on. I've always preferred using a brush for the rest of the colors, as it usually gives you a lot more control and better definition.
When I'm done, I usually give the whole gun a couple of three coats of Testors clear, flat lacquer. It flattens the finish even more and adds a couple of layers of protection.
Here's a couple I've done over the years....
German Flecktarn
These have been painted for about 20 years now. The upper one bounced around in my truck for quite a few years and although you really cant see it, its finish is a little rougher than it looks in the pic. The lower one has been used a little more and never touched up.
Winter layoff and boredom arent necessarily a good thing...
