Do you use your Glock for self defense outside of your house? If not, then I would sell the Glock and keep the Mossberg for home defense. If you need the Glock for your car/concealed carry, I would keep Glock and sell the Mossberg. What type of rifle are you wanting to get? (preban/postban, AR I'm assuming) It would be preferable to keep the Glock and shotgun, but it you ABSOLUTELY must sell one, then look above and take the money you get and put it toward the rifle. You need to realize that when you sale a firearm (if it's for less then you paid), you will be losing money and that just makes the other guns more expensive because of this fact. Saving up for the rifle would be ideal. Maybe you could build you a budget AR from a lower and upper. Should be able to do it for less than $600 if you find some decent deals, depending on what you want. Probably not much help, just something to think about.