What're the differences among forged, cast, and from-billet M-14-type receivers?
First, please note that M1A is a registered trademark of Springfield, Inc. and can be used only by them to describe their M14-type rifle.
Most M14-type receivers are investment cast; among them: Fulton Armory, Springfield, Inc., Armscorp, Smith. There's the new Entreprise Arms receiver that's supposed to be machined from a billet (a solid hunk of steel). There have been offers of forged receivers but to the best of my knowledge none ever made it to market, save one: the PolyTech/Norinco M14S.
Of course, even cast receivers are machined after coming out of the mold, as are from-billet and forged receivers.
The M1 and M14 were designed to be machined from forgings. The sections and dimensions were designed for the forging process. It's difficult to cast the thin sections of the receiver rails, for example, without distortion. That's why Ruger Mini-14 receivers look so clunky: they were designed to be cast.
My personal belief is that forged receivers are potentially strongest, followed by billet and then cast.
However, that's only part of the story. More salient than some theoretical strength limit is the qualiy of the receiver: its dimensions and geometry. That's why Fulton Armory is so "down" on Fed Ord receivers. Check the Fed Ord entry in the FAQ.
Correspondingly, that's why Fulton Armory is so "up" on our own Fulton Armory M14 and the Chinese receivers; wonderful geometry.
When push comes to shove, Fulton Armory recommends its M14 receiver. We offer a 30-day return privilege, and a twelve-month/12,000 round limited Warranty. Let us buld you a rifle for life!
Hope this answers your question!
--Walt Kuleck
Addendum from Clint McKee:
In any case, do not buy a rewelded receiver/rifle, no matter who says so. Unless ofcourse, you want a display piece (read this as wall hanger).
M14 type receivers are *case* heat treated to (if mil spec) 60+ Rockwell "C". This is commonly known as "file hard." The case heat treat is 12-18 thousandths deep, with the core dropping to 28-35 (or so?).
This issue has been repeatably addressed. When welding such a material (8620 steel) heat treated to a case of 60+ Rockwell "C", the weld will create micro fractures (best case) or other stress fractures that will result in possible/likely cracking of the receiver. Very Bad!
Why do or buy such a thing?
--Clint McKee
