model 1 burned me bad after ordering several kits they sent the wrong stock in one, so I returned it and they kept it calling me a liar.
their parts are also NOT mil spec. They are cheap for a reason and now I know.
Rock River, DelTon (uses DPMS), CMMG, Spikes, are the way to go. Stay AWAY from model 1 and M&A sales, its well known in the AR world they are for newbies who dont know better.