Precision machined from ordnance grade steel and meant to interface in shut tolerance with the aluminum stock chassis. Some rocket surgeon drilled and tapped this normally-pristine stainless Mini-14 for an aftermarket scope mount. I had been thrilled. I stuffed the holes with stubby tiny Allen screws and saved about $400. https://franciscovjtgq.blogvivi.com/32271611/helping-the-others-realize-the-advantages-of-magpul-stock-shotgun