Help to ID .45 ACP production period


Hello, gentlemen!
I kindly ask to help me identifying the production period of this .45 ACP REM-UMC cartridge.

Thanks in advance!



1912 - 1952


Ray–I would refine that date to 1912-1920. In 1921 Remington Arms Co. changed to Nickel Plated primers.


Ron - I’m not sure that is totally correct. I have a buff-color box with green print. The Company name line
"REMINGTON ARMS COMPANY, INCORPORATED," and has the addresses Bridgeport, Con., Ilion, N.Y., and Kings Mills, Ohio. I am not sure when the box was made - I don’t see it on your article on this site, although I am sure
I sent a picture of it - but I am of the impression that is later than 1921, perhaps a WWII - era contract box. The cartridge is identical to the one Ivo shows, except it has a very dark blue (almost black) primer seal which I think is characteristic of some contracts in WWII. It is “hardball” - that is, 230 grain FMJ RN GM bullet, brass case with cannelure and a copper primer cup, headstamp: REM-UMC 45 ACP (no punctuation dots in the caliber marking at all). If I am wrong about the era of the box, then I respectfully withdraw my comment about the probably era of the cartridge. By the way, the lot number is illegible on the bzck of the box, but appears to be a letter, followed by a two-digit number, followed by a gap, folled bythe letter D. Index number on the box is R397A. The inside of the end tabs say “Oilproof” on them, if that is any help in dating the box.

The back label mentions "adapted to Colt Automatics and Thompson Sub-Machine guns,: another reason I am prone to think the box is post-1921, since that was the very first year of commercially available Tommy Guns, to my knowledge.

I know you were talking about commercially headstamped rounds when you gave the dates for the end of copper primer cup use, which is why I didn’t mention military-headstamped rounds, since the military specifies the primer cup along with other specs. But, the above are, as I mentioned, commercially headstamped.


So educate me here. In my 45 Auto examples I have W.R.A.CO., U.S.C.CO., and PETERS; and 1917 and 1918 U.S. military cartridges with cupro-nickel jacketed, presumably 230-grain, RN bullets. Initially were all the 230-grain RN bullets cupro-nickel jacketed? If so, when did the general changeover to gilding metal jackets occur? Second, W.R.A., REM-UMC, and PETERS changed over from using 45A.C. or .45AC. or 45 ACP to a common designator of 45 AUTO at some point. Did that occur at the same time and do we know that time?


The only CN jacketed Cal .45 M1911 was the very first production. In January 1912 it was changed to GM, tinned, until 1926.

I can’t speak to the others but commercial REM-UMC used the headstamp 45 ACP from the beginning until 1952 when it was changed to 45 AUTO.



So my W, REM-UMC, U.S.C.Co., and P.C.CO 1917 and 1918 ammo has tinned GM bullets? Is there an easy way to differentiate tinned GM jacketed bullets from CN jacketed ones?


Ray–You are correct when you said I was referring to commercial production with the change from a Rounded Copper primer to a Nickel Plated one in 1921. With that Flat Copper primer it is most likely a military contract round. It may have been for a foreign military, not necessarily the U.S. Army. Also, National Guard contracts may have been different from the Regular Army as far as the headstamp requirements. Also, pre-WW-II contracts did not always specify the headstamp, so the commercial bunter could very well have been used. Your box with “King’s Mill” on it puts it after 1934 when Remington acquired Peters. The “R397A” Load Index Number puts it before 1946 when the number was changed to a four digit number (6645) without the “R”. Your “R397A” is interesting. The only Load Index shown in the catalogs is “R397” without the “A”. I suspect the “A” indicates a military contract.


d’Artagnan–Yes, as Ray said all the “Silver-Looking” .45 ACP except the earliest ones are Tinned, not Cupro-Nickel. There is no easy way to tell them apart (I’m now speaking of all bullets, not just .45 ACP) except by a general look you learn to recognize through experience. The “Tinned” bullets tend to have a flatter finish look to them. Although I don’t recommended it, unless you have duplicates from the same box, you can always scrape the bullet. If it is tinned you will see the coppery GM, which if it is Cupro Nickel will show only silvery. Also, often with Tinned bullets, because of handling, etc., some of the GM will show though the thin tinning, especially at the bullet tip.


Ron - not that it matters, but the information about the buff and green box and its cartridge were from me,
not Ray. Ray probably would not have had any question, as did I, about its time period, as he is far more
knowledgable that I on that type of detail.

Regarding CN vx. Tinned jackets, the easiest way I find to separate them is the color ton. CN bullets have the look of silver, with a yellowish under tint to them. Tinned bullets are generally darker and with a definite gray coloration. Then there are chromed bullets, like much Czech SA ammo, which gleams pure white (some would say silver) with no other under tone to it.

I agree with you that sometimes it is very difficult to tell the difference between the three, especially if a cartridge is not in new or nearly new condition. With tinned bullets, sometimes you don’t even realize they were tinned when you first see them, as all the tinning is gone, leaving a plain GM jacket. If I am suspicious that a
bullet might have been tinned, and was not made as plain GM, I carefully tap it out just a tiny bit with an inertia bullet puller, hopefully not even enough to badly deform the crimp. You will see the thin line of tinning that way that was originally inside the case. I then note it and just push the bullet back where it was.

It is absolutely true what you (Ron) said though - the best way to tell is through experience.


CN on left. Others are tinned.


Excellent picture. Really shows the color tint differences. On poorer condition rounds, it will not be quite so
evident, but a close look will usually tell what it is.


I’ve gotten a real education today. Thank you. Once again I stand in awe before the knowledge and experience of the people I find on this forum.


Thank you very much, gentlemen! You are great! What source of info!
So as far as I uderstood this is ciommercial round of WWII era? Am I correct?



Ivo–In my opinion it is a military contract round with that flat copper primer, not a commercial round. To my knowledge, all of Remington’s commercial production would have used a rounded copper primer up to 1921 and either a rounded or flat nickel primer from 1921 to 1960.The headstamp was changed to “R-P” in 1961.


Ivo - I agree pretty much with Ron. The box for the round I described, which aside from a primer seal of dark
blue or purple (it is so dark it looks almost black) is identical to your round, is definitely a contract box type, not a
normal commercial box.


Excuse me, gentlemen, I’ve not readed your posts carefully enough - it turns out to be WWII era military contract cartridge (I supposed that, but only intuitively). Thank you very much for information!
One more question - was there other types of military .45 ACP ammo than abovementioned “hardball”?




Lots. For example there are military tracer and shot loads and of course match loads. Shot loads were for survival use.


Ivo - also there were training blanks, helmet test loads, roll test loads, high and low altitude cable cutters (bomb cluster release cartridges), proof loads, at least one grenade launching cartridge for the M3 SMG, probably semi-experimental, dog-training blanks - all these not to even mention some CIA types. If one collected every date and month on the headstamps, and every single loading of only US military .45 ammo, they could still have a nice collection running into hundreds of rounds, I would think. Have never tried to figure that out as I don’t collect dates.

The .45 is not as varied as is the 9 mm Para - no pistol caliber is - but it is a handful if one includes all countries, civil and military, and all variations. It is very, very easy to have well over 1000 specimens, and I suppose a really good collection would have twice that.


John, regarding your earlier-mentioned Remington box - If it includes a Kings Mills address, would it not have to post-date 1934 when Peters was sold to duPont-Remington?