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Sonjohn

Receiver Manufacturing Process?

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Does anybody know how the Johnson receiver was made: milled, or forged,or cast,  or welded, or some combination of methods?

It looks like it would take a whacking great bar of steel if you wanted to mill one out, with most of it ending up as waste.

Does anyone know what type of steel was used? Was it case hardened or tempered right through?

Many thanks.

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I have done a little more research on the 1941 ID page here, and it appears the receiver was made from 2 parts welded together. Action milled or forged, and the barrel shroud made from heavy gauge sheet steel. My copy of Johnson Rifles and Machine Guns, 1968, ed Don B McClean, page 14, shows a full length receiver, set up on  milling machine. I'm not sure if this is just a publicity photo with a finished receiver on the machine, or whether it is a true reflection of the actual manufacturing process?

I thought one of the advantages over the Garand was that it was easier to manufacture the Johnson? This process sounds more complicated than  the forge/finish milling of a Garand receiver, which is much smaller due to not having an integral barrel shroud.

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The receivers were forged from high quality 6000 series steel.  Likely first step was to fit in a jig to establish zero points and then drill through the bore.  After drilling, the bolt way was broached on large double acting machines.  These were extremely accurate and fast.  Other broaches made other cuts much faster and more accurate than milling machines. Other cuts were made with a vertical shaper using jigs.  There were many jigs which held the receiver for drilling through hardened bushings on gang drills, each hole or cut had its specific tool.   The work books detailed each step, it tooling and sequence.  These techniques were widely used and were probability as fast or faster than early CNC.  There is a U-tube about making WW1 guns which show this means.  Johnson hired the best engineers and  designers who had years of knowhow.  I have seen the receiver drawing and am amazed at the hundreds of dimensions on one drawing.

The hand guard section was punched in the flat and then formed into shape, the mounting blocks for the screws were riveted in to hold shape.  Likely the barrel latch was also installed at this time since shroud was easy to handle.  The forged piece and the shroud were fitted into a custom welding machine which aligned and welded them together in less than a minute. 

The assembly was probably stressed relieved after welding as neither  the receiver nor shroud were hardened.  Internal parts were hardened as needed.  As an mechanical engineer and machinist, I admire that such an organization  and product came together so quickly and functioned so well.  Comparing to the Garand which was years in design and had its early problems, then produced with unlimited gov. funds and had hundreds of special machines and thousands of people is not a fair comparison.  Both weapons functioned well and met specs during wartime needs.

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