I haven't seen much from those who've actually tested or extensively shot the 20-round mags, but...
I DID hear again from a good friend in Prescott that the 20 & 30-rd steel Mini mags were being supplied USA. He said the Ruger drawings are toleranced but do not have any unique heat treat rqmts for the lips, etc. Also that the plastic SR-556 mags were contracted through Magpul. No word on "special" Ruger engineering requirements for those.
Dunno about the others, but I presume the 5-rd mini mags with the logo plastic baseplate are in-house, although sub-contracting them wouldn't surprise me these days.
Free advice: --GET YOURS NOW before the Dems move onto their next "save America" agenda issue!!!
