Hello All, I'm new to this forum and tried to successfully use the search function but can't find the answer specifically I'm looking for. I have ordered a Mega Ma-ten combo, SI 20" barrel with extension, and a troy MRF 13.8 quad. a Mk 11 civilian style copy... When I receive the barrel from SI, is it necessary to take the rifle to a gunsmith to check the headspace? will any thing need to be done other than screw the barrel in? SI said the barrel extension was headspaced for a DPMS bolt so thats what I got. They offered to assemble the upper if I send the parts in, but for a fee; is it worth doing that or is this a simple task? I also purchased the troy rail that is AR10/DPMS compatible, so hopefully it is the correct height for the MA-TEN, I've stumbled across some negative review from 2009 on the MA-TEN with Troy rails in the early times. I have sent rifles out to be accurized but the smith I contacted no longer does AR's. Can anyone recommend a smith? Is it necessary or will it be plug-and-play with a DPMS barrel ext and bolt? Thanks! <munch>