Originally Posted by AJ100
I have my Dad's 10-43 IBM carbine. He brought it back in 1946. SSgt. 806th TD. It has been around since I was a kid. I'm turning 60 this June so I have been around this rifle for a LONG time. The last time it was fired was probably around 1967. My dad never bought and sold many guns over the years he was alive. I can remember him buying one or two shotguns but that was about it. He had very little interest, unlike most of us on here, with shooting or collecting. He brought back two Jap rifles with bayonets, two swords, a flag, and a rattan prayer mat when he returned from the Philippines. How he got his hands on a V42 knife while still in the states is another story.
I mentioned all this because I know he never had anything done to this carbine. We almost never shot the thing. After some research on the net and the CMP site I can see the stock and all the parts that are stamped are stamped with the correct IBM markings. Except the hammer. It has the letter U with a punch mark on each side stamped on it. Underwood I assume. I did learn that the letter U was also used for Union Hardware. That is what I want to know about. Did Union Hardware make hammers for IBM or did Underwood supply some hammers to IBM when they ran short? Or could my Dad have swapped it out during a cleaning session 67 years ago?
You were correct in your first assumption - the hammer is Underwood. Correct hammers for an IBM M1 are the straight 'type C' marked "U", "WMB", "GMB" or "AMB". So you can be confident that your father did not swap out the hammer.
Most of the suppliers of M1 parts were subcontractors to one another. Metal was in short supply and manufacturing was not as flexible as it is today. When they set up to run trigger guards, they ran a bunch of them before they retooled and ran front sights. Therefore when they were building guns, it was somewhat rare to have all the needed parts on hand. This is where over/under runs were compensated by having a subcontractor agreement in place with other manufacturers. This allowed them to balance stock and help each other out for the greater good of the war effort.
Of course you know that M1s that came back to the armories were refitted with any parts on hand. There was no effort to keep IBM/Underwood/Rock-Ola/Inland/etc. 'pure' since all of the parts were interchangeable. If you have any other questions specific to your IBM M1, let me know.
I have an IBM that was bought brand new through a GI payroll deduction program by a soldier that served in Korea. They took it our of his pay while he was fighting, and when he returned stateside, it was waiting for him. I bought it from his son who had inherited it. As far as he could remember, it had never been fired. I can't find any evidence to indicate otherwise. It sounds like your father's M1 is not much different. I am an IBMer, so I love to collect nice IBM M1s. If you ever decide to part with yours, please give me a shout. I would appreciate the opportunity to care for it!