Question for the guys...I'm number 22 on max10/15 list and almost as low on the max11A1/15 list, may not can afford both at first, my question is how hard it is to change barrels in these uppers, I know that a lot of guys change them in the for M11/9. For my Max 10/15 I want to put in a 14.5 or 16 in heavy barrel and add a bipod like the video floating around of a review of Max11a1/15, I've got 3 Mac 10s so I'll leave one like that, gonna get ARRM system, my Mac 10 for it was made by Sam from an old registered flat, so I don't mind drilling hole.....and I have assembled many AR15s so I should be able to change barrel in it, right? It has a pretty rough finish now and I'm gonna leave it rough, so Mr. Lage if you read this I'll take a less than prefect finish if you get one with a flaw, lay it aside for me instead of refinishing it.