I'm new to this stuff and was wondering about the legal lengths of AR's.  I seen someone who had a 7.5" barrel and seen the new AR's come with a 14.5" and tele stock...  How long is legal?

barrels need to be 16" in over all length .measured from the bolt face to the end of the barrel.for post ban that means you may have a 14.5" barrel with a permanently attached(pinned and/or silver solder) compensator or muzzle brake.with pre bans the same rules apply,but you may have a flash hider instead of the comp.as to the tele stocks,on post ban they are non-functioning and fixed in the fully open  position.mmk