I recently built an M4 clone in .223 Wylde. I also just got five 80% lower receivers, for the purposes of building a couple more in .223W for the wife and the youngest son (14), a short-barrel .458 SOCOM, and a 6.5 Grendel.
Sadly, immediately after receiving them in the mail, they were suddenly and tragically lost in a freak boating accident. Coincidentally, our state just outlawed non-serialized firearms...
