Correct Slide for IBM?

I have #3955066. It has a type 3. A friend bought it from an OLD gentleman in the mid 90's. He claimed his Seabee group stole it and everything not nailed down out of the LSTs arms locker the night before they landed on an island of contested real estate after being issued their " defensive armament " for the duration , a .45 M1911 and 3 loaded clips each. He claimed to have never fired it in anger , but it did give comfort 2 or 3 times. He kept it all this time , but didn't have anyone in his family to leave it to that he'd know would take care of it. It has been taken care of an looks to be almost factory new and orig. , easily in the top two of all the carbines in my collection.
The type 3 did bother me a lot , but , man , it just looked right. The lastest indications are that some of IBMs subcontractors might NEVER had upgraded to the type IV.
Chris

Charlie I have 3857121 and it has a type 3 slide believed orignal as mfgd. to the carbine. hth.

Carbine club newsletter says EM-B bolt (Endicott Machine co.) shows up sporadically from 3881xxx > 3953620. 85% of IBM carbines had either flat or round AOB bolts. There was a transitional period from 3744xxx > 3849xxx where both flat and round bolts were used (AOB).

IBM did not start using the round bolt until early 1944. In January 1944 AO had a problem with their bolts and as a result 16000 bolts were rejected. It was not until Feb. that 12,000 bolts made by Union Switch & Signal arrived to help with IBM's bolt shortage. AO was told not to heat treat the bolts they made and heat treatment was done at the IBM #4 plant in the beginning of Feb. AO,Union,Endicott and Standard Computing in that order made the type 3 bolts for IBM.

When was the round bolt design standardized?

The Club newsletter indicates round bolts standard somewhere after serial 3849xxx

It was before that, as the NL indicates.

Hi Charlie, well I have to admit your slide question got me curious about my IBM so for the first time in over a year I took apart the IBM to see which slide was in mine. Turns out that I have a type 3 marked AOB with a "G" stamped about one inch above the AOB. Anyways, I figured it was about time to oil the metal while I had it apart. I imagine I should oil the other carbines as well :cool:

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Originally Posted by Magnum Mikie

Hi Charlie, well I have to admit your slide question got me curious about my IBM so for the first time in over a year I took apart the IBM to see which slide was in mine. Turns out that I have a type 3 marked AOB with a "G" stamped about one inch above the AOB. Anyways, I figured it was about time to oil the metal while I had it apart. I imagine I should oil the other carbines as well :cool:

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Hey Mike, you have to get 'em out and stroke 'em every now and again. :)