I.B.M stock markings

[Hecklerusp45]

I found a IBM carbine in a local shop. It has a mark on the stock that is U with a dot before and after the U. What does that mark mean?

[Tuna]

A large U most likely on the left side of the stock means that at one time in the late 1940's the stock was on a carbine that was rebuilt by Underwood. They and Standard Products had contracts with the military to update carbines. They did at least 400,000 carbines changing rear sights, safeties, magazine releases and of course barrel bands so carbines could have a bayonet on them.

[Hecklerusp45]

Thanks for the help Tuna. I appreciate you sharing your knowledge.