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Iver Johnson Compatibility

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floydthecat View Drop Down
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    Posted: Jun 02 2020 at 8:44am
Compatibility with USGI parts. I’ve played-around some with commercial carbines, both Universal, Iver Johnson and Plainfield.
Just as a note of interest, we often see remarks like “completely USGI compatible”. I have determined the gen 1 Universal is usually true to that idea, but other commercials not so much. In particular the bolts. Iver Johnson bolts are a tad longer in respect to the rear of the right bolt lug and the bolt-face. Carbines that were built using IJ bolts generally will not head space if trying to use Universal or USGI bolts. You might get by with a GI bolt, if it is on the long side. More often than not you might take a 1.297 chamber out to a 1.310 chamber by swapping an IJ bolt with a GI bolt in an Iver Johnson action. Conversely, an IJ bolt will be too long for a action built for a GI or Universal gen 1 bolt.

Just useless information I suppose, but for those considering a bolt change to harden a commercial carbine, or as a cast bolt replacement might be interested. 
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sleeplessnashadow View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sleeplessnashadow Quote  Post ReplyReply Direct Link To This Post Posted: Jun 02 2020 at 11:02am
Hey Floyd

Couple things.

Universal, Plainfield, and Iver Johnson were around for awhile. What they made and did changed over time. It's hard to class all bolts by Universal the same, ditto Iver Johnson, and Plainfield to a lesser degree.

Iver Johnson's sale to the Arkansas group, in Arkansas they went thru a number of alterations to include using Universal carbine parts since they bought Universal when they bought Iver Johnson. When they went Chapter 11 and Lou Imperato took back over he also made changes.

All that said ....

My opinion, no commercial bolt should be used with a GI hammer. No GI bolt should be used with a commercial hammer. Fulton Armory being the only exception.

None of the commercial bolts were/are hardened a second time to bring the rear of the bolt to GI spec. A GI hammer will deform the rear of a commercial bolt and defeat the safety mechanism built into the bolt design.

For others reading this, any and every bolt change, GI and non GI, needs to be checked for headspace with the barrel. Ditto every barrel change should be checked for headspace with the bolt.

Jim
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floydthecat View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote floydthecat Quote  Post ReplyReply Direct Link To This Post Posted: Jun 02 2020 at 1:06pm
I agree with all that. I have a couple of IJ’s around here that have Universal parts. One with the late Universal round firing pin and bolt and it closes on a field gauge. Stuck a known IJ bolt in it and it head spaces about 1.296. I thoroughly inspected/compared the bridge-cut to my GI carbines and it passes muster for a GI style bolt and pin and hammer.

They likely used whatever they had that would fit toward the end of production. Blended-in what they had I guess. Only reason I have any is because IJ was the only one that manufactured a 9mm and a stainless 30 spec. USGI, or close to it. The stainless 30 is mostly for just having. I shoot the snot out of the 9.
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