I currently own multilpe pistols and am looking to purchase my first assault rifle. I am looking at either an AR15 or AK47. I have a dumb question and would also like some advice as to brand / model reliability and where is the best place to purchase one as our local gun dealers inventory is almost non-existent. Do all current assualt rifles come in single shot, burst and fully automatic? Most everything on Utube is fully automatic - where do they get them?