I'm brand new to this forum but sure as hell wish I would have found this before I ordered my Handl Defense SCAR 25 lower in FDE. I waited approximately 3 months to get the lower. I got it in April but just had to guts from my stock lower swapped over into it by a local gunsmith. When I picked up the SCAR 25 lower the gunsmith told me the openings for the parts were extremely tight. I got it home last night and tried attaching it to my upper receiver with no such luck.
It literally would not slide into the rear portion which would allow me to push the pin into the front take down hole. I filed some of the material off so it would slide into position at the back plate. This did allow the front part of the lower to slide into place, however the take down pin was a pain in the butt to get in. Once in, it left a gap almost an 1/8 of an inch gap between the upper and lower near the take down down pin.
I bought it from Rainier Arms and they want me to email photos and go from there. I seriously hope they can fix it or replace. I may be screwed. In one of the photos you can tell where they drilled/machined the take down pin hole too high, causing the gap. First photo shows the gap formed from the take down pin hole on the new lower being drilled too high, causing this issue. Second photo shows what I had to do to the end of the new lower just to get it to seat correctly in the back plate. Last photo shows the difference where the take down hinge pin hole is compared to the stock lower.
SCAR25 lower with guts with gap closeup.jpgSCAR25 rear filed to fit.jpgSCAR25 with guts installed with gap.jpgStock and SCAR25 Pivot difference big time.jpg