" Anderson " upper receivers

[ruger44srh]

I just got 2 Anderson uppers with the forge code M with an upside down triangle above it. Goole-fu said it was from Mueller Industries, a plumbing manufacturer. It also said Colt has used them for forgings. Anyone have anything pro or con ? This is the first time seeing this forge mark for me.

 

[aaron580]

Yes mueller is a supplier of uppers. I don't have much knowledge in what way, but they never provided any uppers with a c stamp for colt. cmmg, maybe Anderson, and other manufacturers have used mueller marked uppers. also another little known coltompany "demco" supplied mueller uppers for dod contracts as well, but I personally cannot confirm 100%.