upper/lower reciever manufacture marks?

[Country Boy]

is there anyway to know where the forgings came from?

[Stickman]

Yes, the forge markings give that info, but it is useless as it will not tell you who machined the receiver. There is no quality difference between them that I've ever seen or heard of.

[Country Boy]

so then the main thing that contribues to "quality" are the tolerances used in the machining process and not so much the house name?

[mhanna91]

Yep, it is the machining that makes quality. Out of spec and loose tollerance pin holes and mag wells could cause problems. If you stick with a known quality manufacturer you should be fine. Head over to the Noveske website and check out their hand-fitted stripped upper/lower combos.

[Quentin]

Just make sure the receivers are made of milspec 7075-T6 alloy which I believe all the top brands are. There are differences in machining other than tolerances, such as beveled out magwells for easier mag insertion and smoother finishes. Of course it's mostly cosmetic but I was very impressed with the stripped S&W M&P-15 lower I bought last year. Really fine work.

[Stickman]

so then the main thing that contribues to "quality" are the tolerances used in the machining process and not so much the house name?


Very much so. The forging itself is oversized, and everything needs to be machined on it. There are different allowable manufacturing tolerances on upper and lower receivers, which is why some lower receivers won't drop magazines, and others will.

The end machining process and the specs they are held to is much more important than what name is on the side. However, the name on the side is often a good indication as to the quality of the component.

Hopefully that makes some sense.