I am looking to purchase in the next few weeks. I want some sort of assault rifle....probably an AK. I need a larger caliber handgun....a .45 or something. I also want to convert my Remington 870 into more of a combat type weapon. I saw on another link a tube that increases the shell capacity by 5 more. My barrel is 25", had it cut down several years ago. Would that tube stick past my barrel? Give me all your suggestions including optics.