07 PMR - Comes stock with composite frame, trigger, bolt cap, eye covers, and possibly feedneck.
08 PMR - Same thing as 07, basically a Special Edition. Comes with all metal parts besides frame, and has a two piece barrel.
09 PMR - Comes stock with a Dye UL Frame, new milling, Hyper 3 reg, redesigned solenoid, and On/Off ASA.
2010 PMR - LOL no change, except new milling and color coded O-rings.
2011 - they drop the name PMR and make Proto Rail and Proto Reflex Rail.
Change bolt from this:
Rail - One piece barrel, "NEW" composite frame, Still Hyper 3, added an eye pipe like the DM's, No On/off ASA and of course new milling. Has an "inline" ASA and steel-braided hose instead of macroline. Also has an awkward looking straight fitting on the reg.
PRR - 2 piece 14" barrel, Dye UL frame w/o Dye logo now, eye pipe, Finally a cam lock feedneck instead of an allen wrench, and On/Off ASA. Different Milling.
2012 -- Don't make a new Rail, Only Reflex this year.
PRR - Seems to be the same milling. New PGA Anodizing, Comes with DM "Ironmen Blade" trigger, but they seem to be calling it the Reach trigger, which I'm pretty sure is the previous one, and has a "cam drive" ASA instead of "gear drive".