Quoted:
Mboylan - I know that drilling the hole for the sear pin OS the same as drilling out the Y axis on an AK and have no intention of doing so. I just want a receiver milled in a manner where that is all that is left to do for it to accommodate an auto sear.
Circuits - I have heard of the "Plum Crazy" lowers, in another thread, but didn't realize they were plastic. What problems does this create? Any?
Well, a "receiver milled in a manner where that is all that is left to do for it to accommodate an auto sear"
cannot be used with an RDIAS or an RLL –– they will not function in a receiver milled that far open.
So the only purpose or reason to need a receiver fully milled out is
to manufacture a machine gun–– illegally or, if you are a licensed 07/02 manufacturer, a post-sample MG for sale to LE/mil.
AFAIK, no U.S. manufacturer has ever made such a receiver in metal for retail sales. There was one foreign manufacturer who imported a bunch of cheap milled-out-but-no-autosear-pin-hole-drilled receivers a few years ago –– I know because I got a ton of calls from FFLs who wanted to buy them but were concerned about their legality. I told them that they were indeed legal.
Now, many U.S. manufacturers will do limited runs of milled-out receivers, but only under contract to licensed 07/02 FFL/SOT manufacturers. The potential liability is just too great for them to sell milled-out receivers to the general public.
If you really want one, I suggest you buy a mill and learn how to mill out semi-spec receivers. But if you do so, you are on your own as to legal issues. I'm not a lawyer and this is not legal advice, yada yada yada.
The plastic Plum Crazy receivers are fine for semi, but I have no idea how they would stand up in full-auto function.
HTH. YMMV.