U.S. M1911 & M1911A1 Inspector Reference

Inspector initials, names, and the pistol ranges where they are commonly encountered.

Inspector Initials by Serial Range

Inspector Initials	Inspector Name	Approx. Serial Range	Commonly Seen On	Notes
J.M.G.	Major John M. Gilbert	1 – 23000	Early Colt M1911	Used on very early Colt military M1911 pistols.
R.C.D.	Major Robert C. Downie	23001 – 85000	Colt and Springfield Armory	Seen on early production pistols before W.G.P. became common.
W.G.P.	Major Walter G. Penfield	85001 – 290000	Colt and Springfield Armory	Common WWI-era acceptance mark.
G.H.D.	Colonel Guy H. Drewry	Approx. 700001 – late WWII	WWII Colt	Commonly associated with WWII Colt M1911A1 pistols.
F.J.A.	Colonel Frank J. Atwood	WWII contractor production	Ithaca, Remington Rand, Union Switch & Signal	Important for identifying Ithaca pistols in duplicated serial ranges.
R.C.D.	LTC R.C. Downie	WWII US&S production	Union Switch & Signal	Also associated with Union Switch & Signal inspection references.
J.K.C.	LTC John K. Christmas	S800001 – S800500	Singer	Associated with Singer contract pistols.
H.S.	LTC Harrison Shaler	Remington Rand production	Remington Rand	Listed as a Remington Rand inspector reference.

Manufacturer Inspector Reference

Manufacturer	Inspectors / Inspection Initials	Notes
Colt	J.M.G., R.C.D., W.G.P., G.H.D.	Inspector marks vary heavily by production period.
Springfield Armory	R.C.D., W.G.P.	Used on early U.S. military M1911 production.
Ithaca	F.J.A.	F.J.A. is especially important on duplicated serial ranges.
Remington Rand	F.J.A., H.S.	Common WWII contractor inspection references.
Union Switch & Signal	F.J.A., R.C.D.	US&S pistols may reference Atwood or Downie inspection data.
Singer	J.K.C.	Singer contract pistols fall in the S800001–S800500 range.

Note: Inspector information should be used as a supporting identification aid, not as the only proof of originality. Always compare serial range, frame markings, slide markings, finish, proof marks, and rebuild markings together.