Underwood Bolt ?

[mpd1978]

What is the earliest Underwood Carbine that anyone has seen with a SU marked flat bolt?

Information

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[painter777]

I'll try to find some time to sift thru the CC Newsletters this weekend.
At this point I couldn't throw out a guess.

Charlie-painter777

P.S. who might the maker be? S ? Maybe standard? I'll look over War Baby also.
Any picture available?
Is the SU marked under the left lug?

[mpd1978]

I actually dont have the SU bolt at my location, but I think its marked under the lug with SU. WB reports it could be correct,but some of the other books say it wasnt used until later production. Anyway the carbine is a really nice original 1.39 Underwood, the issue is someone scubed the hell out of the top of the bolt removing the rust and all of the bluing. I was debating on swapping the SU bolt in its place since it is still wearing its blued finish. I hate to take out original parts, but it sure looks like crap in the gun.

[painter777]

I've cleaned up and prepped the bolt on ones with zero finish left and used that Brownells Oxpho creme. 1 was a SG bolt someone had used a black sharpie on the top flat, the other a IBM round will no finish left to speak of.
Put some in a zip lock and soak the part for 2-3 days. Comes out with that blue/black look much like the color I've seen on original SG/S'G' bolts still in the blue. Color looked just like the 2 new original extractor's color.
Trick is just don't buff the finish down to where it gets shiny. Just lightly wipe off the left over creme and lightly oil.

Have a pic of a IBM bolt I used it on. Not a close up but here it is.
And the SG bolt with the sharpie touch up by Bubba.

Could take better close up pics this weekend if you need or are interested in them.

HTH,
Charlie-painter777

[mpd1978]

Good info about the Oxypho creme, i will keep it in mind. Thanks

[Bruce McAskill]

An SU bolt is correct for your serial number so it will work for you. Underwood started to use the SU marked bolt about the middle of to the end of February 1943. Your serial number dates to about April 1943 so you ahould be alright with it.

[painter777]

So,
It comes down to swapping another bolt on it,
Or refinishing the 'Original' bolt that it came with.

MPD1978,
More decisions for you

Bruce McA,
Who made the SU bolt?

Thx,
Charlie

[Bruce McAskill]

Charlie, SU marked bolts were made by United Shoe Machinery Co.