Hardness Dimples on June 1942 manufactured Inland Receivers

[painter777]

Carbines were listed in the Critical list a few times.
IMO Inland wanted to show WRA they weren't going to be the warm up band. A healthy competition to speak. But there were other factors involved like previous contracts WRA was knee deep in.

While searching for something else today I ran across this picture of my WRA 1,030,621. Now IMO WRA didn't have the prettiest milling you'd find. Often showing vice scars, voids, pits etc.

I noticed this circular dimple above the trigger housing pin. Thinking about the thread...... Do you think this is a hard ness punch? Me ? IDK

Thread link: https://www.milsurps.com/showthread.php?t=38393
Picture from page 3:

[Hammer]

I also wondered if the indentions could have been "anchor" points or index marks for a milling device, maybe for the slide rail on the opposite side of the receiver, but if it was there would have been two different anchors because of the two different round indention sizes. It also would have been for a process that was changed sometime after mid August 1942 since there doesn't seem to be any of these indentions on receivers after that time. When the longtime experienced collectors & researchers over on the CC Forum looked at these they collectively felt these indentions were Hardness Testing marks and that's why I've gone down that track here :-)

[Hammer]

Painter777 not sure what that O is but its doesnt look like a hardness test to me but more like an inspectors initial, but it seems the O is slightly oblong and not perfectly round, but that may just be how Im seeing it...

I went and looked at the other pics you posted in 2012 of this Super early Winchester - WOW, Very NICE !

[eb in oregon]

had not there been a discussion of hardness testing, I would have guessed maybe the mark was a witness or index mark showing correct alignment in whatever jig was used in the milling processes.

For that to be the case those dimples would have to be in the exact same place on every single carbine. Jigs and fixtures require an exact location so those dimples would be consistent throughout manufacture for all production. I don't think any company is going to design it's own tooling that's different from everybody else's tooling as the process is supposed to be pretty much the same for everybody.

[USGI]

I don't think any company is going to design it's own tooling that's different from everybody else's tooling as the process is supposed to be pretty much the same for everybody.

IP was doing that until Saginaw took over and made a "few changes." Their set-up for the trigger housings was just one of them. - Bob

[Flying10uk]

The metal has to be hard enough but not too hard. If the steel isn't hot enough before quenching during the hardening process the metal will be too soft. Get the metal too hot before quenching, during the hardening process, and the metal is effectively destroyed; no amount of tempering will repair the damage. For correct heat treatment the steel has to be heated to the correct temperature range for that particular type of steel and then quenched. It then has to be tempered by reheating to the correct, much lower, temperature for the amount of hardness required.

Hardening and tempering seems like an easy thing to do but it is an easy thing to get wrong.

[eb in oregon]

IP was doing that until Saginaw took over and made a "few changes." Their set-up for the trigger housings was just one of them. - Bob

There is a difference between laminated and brazed trigger housings and cast trigger housings. While I've had multiple M1's with cast trigger housings my Inland has a laminated trigger housing. Two fundamentally different manufacturing processes with different construction processes. Not quite the same thing as the receiver and it's processes.

[painter777]

Eb,

I believe USGI Bob is talking about how IP set up their own jigs that Pedersen thought were best. Problems arose because these had to be taken down and set back up for the next steps (Not explained correctly 100%) but their method was causing problems with fit, from 1 to another because of the multiple constant re-setting of a jig for a part. When Saginaw took over one of the first things William H. Doerfner did as general manager of the Saginaw Steering Gear Division of General Motors was scrap IP's jig methods. Then set up proper ones that stayed in place until the part was finished. This made parts that stayed with in specs, also saved on scrap and labor time.
This all from my rough memory. There is a good write up about Saginaw and Doerfners take over and the actions they took. It's in Larry Ruth's War Baby. I have parts of Robert Irwins daily log book passed to me from the family where Robert himself listed problems with Pedersen lack of production skills. Calling him a skilled gun maker but not a production man. Comments on to much hand fitting of parts is included in some of Irwins comments...... Or better said His Writings.
There were reasons not a single IP carbine was accepted by Ordnance, not until after the S'G' take over and salvaged parts were assembled. The checks were made out to Saginaw Steering Gear Grand Rapids Division.

Lastly I can assure you USGI Bob is familiar with a Type IV Fabricated/Laminated/Brazed trigger housing and the Type I, II, III, V Milled ones.

Later,