Round or Flat Bolt for IBM 3,849,xxx ?

[painter777]

Round or flat bolt for IBM 3,849,xxx ?

Thx,
Charlie-painter777

Information

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[painter777]

Manufacture date?
Jan- Feb 44 ?

[VietVet]

Manufacture date?
Jan- Feb 44 ?

Correct

[dbarn]

Charlie, I have 3857121 and it has a round bolt marked AOB with an X on top.

[Magnum Mikie]

Charlie, I have 3857121 and it has a round bolt marked AOB with an X on top.

Same here. My 3,910,xxx also has AOB round bolt with X.

[VietVet]

Both flat and round were used at that serial number. Most common would be the round bolt marked SB

[painter777]

This information was passed to me from a fellow member a while back:

your carbine was made in late Jan. or early Feb.1944. This is when IBM started using the round bolt along with the flat bolt. IBM received 6000 bolts from Union Switch and Signal between Feb. 9th and the 22nd. I cannot prove it but I have a gut feeling these were round bolts. Now Auto Ordnance had stopped making bolts in January due to poor heat treatment and the bolts were breaking. 16,000 were rejected but they later made this up and I think they were most likely flat bolts. To make a long story short I am pretty sure your carbine could be correct with the flat bolt or the round bolt but when you consider that IBM made about 40,000 carbines in Jan. and the same in Feb. 1944 the odds are in favor of the flat bolt being correct for your carbine.

David,
I wonder if your AOB round with the X may have been after the rejected bolts. Possibly making that 'they later made this up' order Round bolts?

I'll look thru the newsletters I have. Just seems like most every carbine I get involved with is near some transition point....makes it hard. Each and every carbine seems to be it's own animal !

Appreciate the help.
Charlie

[dbarn]

Charlie, if I remember correctly the X is to show that certain revisions had been made to the design of the round bolt. It's possible that it was shortly after the rejects. My thoughts are this is a transitional period for IBM. Mine has the flip sight and low wood birch SCB marked stock and hand guard with a type 1 band. Either round or flat could possibly be correct.

[grits]

i have IBM38279xx with round bolt if any help.

[VietVet]

See Newsletter #329 page 5