I have a Mk12 upper (With it’s own BGC) for my MWS set up as a DMR. Currently firing bang on 315 FPS on a .4g bb (318 FPS on a .4g bb is equivalent to 450 on a .2g bb).
I didn’t upgrade much as far as the internals go to get the power and accuracy my list was:
- SixG Brass nub (so I can hop heavy BBs)
- npas valve (so I can tune the FPS, it goes higher as well as lower than stock).
- Maple Leaf Crazy Jet 455mm VSR Cut Barrel.
That’s it in terms of internals. In terms of externals you will need either a silencer or an 18inch outer barrel to cover that inner barrel (I was always going to do a MK12 upper so just chose the longest inner barrel that would fit in the 18” outer).
other than that everything else (sights, bipeds etc.) is optional.
There are other ways to go (e.g tighter bore barrel will get more FPS, so won’t need to be as long), but this was very cost effective and has been super reliable as I’m not messing with spring tensions or other stuff that could impact reliability.
As an aside I have found the stock TM hop rubber to be the best balance of performance and durability. There are hops that perform better (some of the maple leaf buckings and the modify tan spring to mind), but I have found they don’t last that long at DMR FPS.
Edit: just to add there are still a few turns left on the npas so I could go higher FPS.
Second Edit: I also permanently modified the safety/selector switch to semi only (needed to comply with U.K. law). There is a YouTube video on how to do this.