7th Round Stoppage

[Bob Seijas]

I've done a lot of mental work on this subject and I think I know what really happened. The common wisdom is that it was caused by the shearing of the top of the guide rib. IMO that is only part of the answer. The Model Shop guns have sheared ribs and did not experience the 7th round stoppage, the problem only showed up after mass production was well underway. And only a very small percentage of rifles malfunctioned that way. Since they all had sheared ribs, most of them should have seen it. They didn't, the vast majority functioned perfectly.

Add into the mix that Art Tuttle always said it was "a stack-up of tolerances in the follower." When mass production started, machining was less careful than it was with the MS rifles made almost by hand under the personal supervision of JCG, a stickler for "machining to drawing." Workers were paid on a piecework basis, so there was a lot of incentive to turn out volume. In addition, there was an allowable variation from exact drawing dimensions that was acceptable. If you look at the blueprints, you will usually see a +/- figure after many dimensions that specified how far out was OK.

The upshot was that a rifle with a tight follower could tolerate the sheared rib and still function correctly. When a sloppy follower encountered a sheared rib, it experienced the stoppage. Once the rib top was built back up, a loose follower didn't cause a jam. I'm personally satisfied that is the answer.

Information

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[Bill Hollinger]

Great information Bob. Thanks so much. We here at milsurps are very fortunate to have members like you with us.

[RCS]

Springfield stayed with the revision 4 follower and slide from the end of gas trap production to 1941. (I would like to view one of Hatcher's followers with the welded on the slide done for the 1940 matches) The revision 4 started with the low guide ribs.Attachment 54338

There also seems to be some differences in the Winchester followers used just in 1941
The very early Educational Order rifles had the revision 2 (unmarked) that was replaced by the 40 degree long nose and 40 degree rear until mid 1941 where the Winchester follower and slide entered production to almost the end

Photo shows late, mid '41 and early '41

[Bob Seijas]

Don't forget the "Tuttle Slide" in which the back was rounded over by hand. I don't remember why he recommended it, but JCG approved the modification.

[RCS]

I seem to recall that more space between the bolt and slide might help


follower and slide in the center has the round back slide, use to find these years ago but there was little interestAttachment 54365

[browningautorifle]

Quite a pile of parts you have RCS...

[Bob Seijas]

It's a black hole, things get sucked in and never get out

[browningautorifle]

I need to show up with steaks for the BBQ and some Bourbon...and my spectacles. Look into this black hole for a minute.

[Bob Seijas]

I need a Model Shop follower for #3 if anybody ever runs across one. Attachment 54396

[RCS]

Just find someone to make one might be the best way, certain early prewar parts just may never turn-up

I needed an early front sight and the repros did not look that good so I made this one.
The serrations on each ear was kind of tricky but came out ok - Attachment 54399Attachment 54400Attachment 54401Attachment 54402