Polymer AR-15 lower receivers offer light weight, surprisingly high strength and, most importantly, very low cost. Historically they’ve been a bit of a mixed bag in the quality department, mostly due to fit issues caused by molding imperfections. StarLos Firearms has set out to improve on past offerings from other manufacturers by improving the polymer and improving the manufacturing process, and we were happy to put their SLF-15 complete lower through the wringer to see if it worked. 500 rapid-fire rounds? Check. Run it over with my truck? Check . . .
