I've got a friend who sent a bunch of AR 15 parts off to a custom shop. They went out of business and it took a potential law suit from a collection of similar customers to get their parts back. Now saddened he tells me he doesn't know what to do. I told him that since he has four other AR 15's why not put together a .300 blk out? This is when he tells me that others have told him they wouldn't do that and to go ahead and have me put together another AR 15 as he was going to have the shop do. I told him I had no real reason why anyone would tell him that and that I would post his issue with all the like of you who may read and reply to the question. So, why would you not want a .300 blk out? Especially if you already have four AR 15's, three are for the "having" only and are rarely shot.