I am looking to add a +2 to my M1S90 tactical. A friend says the +2 will extend beyond the 18 1/2 barrel but I recently saw a early 90's with one and it was shorter than the barrel. Does anyone have one installed thy can measure or post a pic of? No one carries them locally to me, so I will have to special order one which means no return or high restock fee. Thank you.