M1 Carbine IBM "AO" Receiver Question

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Acquired a very clean IBM carbine a year or so ago, purchased it from a lady who said it belonged to her father. She said he was with the Navy in (or immediately after) WWII, Sea-bees if I recall. She gave me a lot of history about her Dad but nothing to document the provenance of this carbine. That being said, I don't really know if he brought it home with him after his tour or if he acquired it afterwards.

The rifle is in excellent condition, with an IBM barrel (10-43) and a type III barrel band (which makes me think it was an arsenal rebuild during the war). S/N is in the 3852xxx range (1st series?) but I have not "dissected" it yet to check all the internal parts as to manufacture.

My question is regarding the receiver. Behind the rear sight, it is stamped IBM CORP. with the serial number below, and the letters A.O. (Auto Ordnance) stamped below it, indicating a receiver made by A.O. for IBM. However, this carbine also has IBM CORP and the same serial number stamped in front of the rear sight! Basically, it's a double-stamped receiver. I've never seen or read anything about this before, was wondering if any of you experts can tell me more about it. I'm thinking this was probably done when IBM took over receiver production from Auto Ordnance, and perhaps utilized whatever receivers were already made by A.O. and then re-stamped them with IBM. Does this make this any more rare (or valuable) than other A.O. stamped receivers?

Appreciate any and all info on this carbine.

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Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[Tom in N.J.]

I'm not a carbine expert (they have been banned in NJ since 1991), but I believe the serial number in front of the sight was added by the upgrading facility. When the new adjustable sights were installed they covered the manufacturers I.D. and the serial number. Some carbines were re-marked to allow easy access to that info. The practice stopped when they found the original number was readable, the manufacturers name didn't matter for book keeping at the unit level.

[JimF4M1s (Deceased)]

I.B.M. had one serial number block, 3,651,520 - 4,009,999 about 346,500 or 5.6% of carbine production. Your carbine looks to have been built the first quarter of 1944. Making a 10-43 barrel most likely original.

The re stamped serial number indicates at least to have had an Arsenal upgrade sometime. Quick things to look for. Does it have push or rotating safety? Mag catch with the tab for a 30 round mag? Flat bolt? Stock cut for a selector switch? Did it come with a sling, end tabs?

Pictures after you break it down will tell you more. Part markings, things like that.

[Newscotlander]

IBM, or Auto Ordnance for that matter, never stamped the serial number in front of the rear sight. That was done during an arsenal rebuild. The reason it was done is because when the flip sight was replaced with an adjustable rear sight, the serial number was often times covered. See photo from rebuild manual below.

[Newscotlander]

I took another look at the OP's post. He should post a picture of the marking on the receiver. I've never seen an instance where the "IBM CORP" is stamped in front of the rear sight. It may be a one-of-a-kind or "home work".

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I took another look at the OP's post. He should post a picture of the marking on the receiver. I've never seen an instance where the "IBM CORP" is stamped in front of the rear sight. It may be a one-of-a-kind or "home work".

My humble apologies to all -- I checked my M1 again and saw that I was in error, it was only the s/n that was stamped ahead of the rear sight and not the "IBM" stamp. And yes, it does appear to be an arsenal s/n stamp as the numbers are not in perfect alignment as is the original factory stamp. As mentioned earlier, having the type III barrel band and the adjustable rear sight definitely indicates an arsenal re-build.

I will try & take detailed pictures when time allows.....

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