Check the bolt compatibility! I've read conflicting accounts whether or not the M&P 10 is compatible with DPMS bolts/bcg's. Supposedly DPMS pattern barrels fit, so if you use a given barrel and buy it as a combo with the bolt, IMHO they should fit. I did a quick search on the M&P 10 receivers and saw a lot of of conflicting information posted by mostly dipshits who don't know what they are talking about. Some things are proprietary for 308-AR's / AR-10's. Unfortunately, a lot of numbskulls are very interested in the big boy AR's and like to post over and over again despite having zero experience.
Fun project. A little more challenging than an AR-15, but barely. I built a DPMS AR-308 in 6.5 CM, starting from a NES group buy port cover LOL. For long distance I suggest the 6.5 Creedmoor and a high quality barrel and bolt plus a Geissele or equivalent match trigger. I used a Premium Series Ballistic Advantage stainless 20" and it's ~1/2 MOA accurate but if I did it again I'd go 24" for the extra velocity. I have a 24" Criterion match barrel I'm going to try.
My BCG is a JP and I'm using the JP high pressure bolt. Everything else is to your preference. I used a JP free float but I like the looks of the Centurion listed above. For a buttstock, Luth AR's has worked very well for me. I think my upper/lower combo is Andersen or something similar- doesn't really matter as the magic is coming from the barrel, bolt, and trigger. I do use the O-ring trick or a twisted wrap of teflon tape on the rear trunnion to lock up the fit between upper and lower. For long distance shooting this will matter.
I suggest getting the barrel, gas block, and gas tube from the same supplier.
If you know someone or a shop with parts, you can check to make sure the upper works with a DPMS style barrel and even check a BCG. I'm in north central Mass- if you ever head out this way or at least to Worcester and want to check a barrel and BCG fit, send me a PM.
Oh, here's the link to my project. Receivers were Aero Precision.
Done! Aero M5 in 6.5 Creedmoor