jiannichan wrote:I want something a little more discreet when I want to bring my rifle out of my home to take into the car. I just moved into an apt so, I don't want to carry out a tactical bag where the neighbors can see.
Interesting project. I don't know much about the Great Stuff urethane, but a quick Google shows that it is prone to settling. It sounds like you will work out your issues. I suggest that you let the plastic cure for several weeks with the case open so you can be assured of a complete cure. Outgassing will occur and you want to make sure the vapors don't damage the finish on your gun.
My question for you is "Do you play the guitar?" It might arouse suspicion from your neighbors if they see you carry this case and find out that do don't play or even own a guitar.