A made by ?
AM made by Springfield Armory
BRW made by Borg-Warner
BRW S-1 made by Borg-Warner's Automotive Spring Division.
(Others say it was Borg-Warner's Brake Division in Winchester, Virginia.)
BRW B2 (set in circular pattern) made by Borg-Warner
C.M.I. made by Check Mate Industries of Long Island, New York
HR made by Harrington and Richardson
H-R made by Harrington and Richardson
HR-R made by Harrington and Richardson
KMT (A stylized logo with large K and the "M" and T" tucked in around the "K")
made by Kileen Machine Tool Company
KMT overstamped with an A (Kileen Machine and Tool Company)
M made by ? Possibly mis-marked magazines made by Winchester (inverted M???)
M with a line under the bottom and also a horizontal slash through the first hump of the M at
midpoint (so that it almost looks like an A and an upside down V connected) with a line underneath the entire M character. Made by Mathewson Tool Company. Some of these were packaged in Springfield Armory boxes.
OM made by Winchester (Back when it was part of Olin-Matheson.)
R (Underlined) made by ?
SA made by Springfield Armory (The original government arsenal, not to be confused with the commercial firm that now uses the name.) These magazines are very scarce and command premium prices.
SHO Made by Springfield Armory (The original government arsenal). This marking is "the rarest of the rare" and was used only on very early production (circa 1959) Springfield Armory produced M14 magazines.
TRW made by Thompson Ramo Woolridge
UHC made by Union Hardware Company (Stamped in an arc)
(Note: Some wrappers for UHC-stamped mags are from Brunswick-Olin.)
W made by Winchester
W (With overscore line and slash through the second "V") made by Winchester
WRA made by Winchester