I've been sitting on a Polymer 80 kit for about 3 or 4 years now. Never got up the time or nerve to mill it out, but finally did this weekend. Upper is a Doublestar HB carbine lenght with USGI milspec BCG. CMMG LPK with ALG trigger group and hammer. PSA Milspec buffer and rear-end. Magpul MOE grip, UTG BUIS.
Only issue is that the Magpul mag isn't tripping the BHO, but CProducts mags and USGI mags will. Not sure what the issue is there, but it's easy enough to just use the CProducts stuff (and cheaper!)
Milling was pretty easy. Used a HF drill press and Shop Fox cross-slide to do it all. Found out (as many others have) that drilling holes to the prescribed depth with a drill bit and then using the end-mill to take out the remaining material was the best way to go about it since end-mills aren't really made for drilling straight down. Kept measuring twice and cutting once and didn't have any issues. Seems really solid. No upper wobble, everything mates up nice and tight. Looking forward to putting some rounds down range with it and seeing how it performs. Now that I've done one, I feel pretty confident in tackling an AR10 next.
Only issue is that the Magpul mag isn't tripping the BHO, but CProducts mags and USGI mags will. Not sure what the issue is there, but it's easy enough to just use the CProducts stuff (and cheaper!)
Milling was pretty easy. Used a HF drill press and Shop Fox cross-slide to do it all. Found out (as many others have) that drilling holes to the prescribed depth with a drill bit and then using the end-mill to take out the remaining material was the best way to go about it since end-mills aren't really made for drilling straight down. Kept measuring twice and cutting once and didn't have any issues. Seems really solid. No upper wobble, everything mates up nice and tight. Looking forward to putting some rounds down range with it and seeing how it performs. Now that I've done one, I feel pretty confident in tackling an AR10 next.
Last edited: