JSAR receiver differences

[Brian Alpert 0]

Has anyone ever noticed that most if not all of the no-prefix (that I have examined) receivers have an irregular "joint" where the radiator is welded and the A and B prefix ones have a well defined ridge machined at this point. It is almost like the receivers were put together on 2 different lines with slightly different finishing jigs. I wonder what accounts for this since the no prefix and prefix rifles were manufactured at the same time. Has anyone else noticed this or have any thoughts?

[diggerj 0]

I never looked closely at my two non-prefix and one A-prefix but will. I always wondered why it could not have been that there were indeed several fabrication lines running (non, A- and B-) and concurrent product made but different. the first jig may have been followed by two more made subsequently when there was a "rush of orders" for NPC. Also never questioned the use of production numbers even though they weren't concerned about using them in any order. I believe they were quality control numbers such that if something were wrong on a production process machine they could back-track from a bad item produced to the point before and after when the item was correct.

(Now I have to dig out the receivers and look!)

Regards all.

John D.

[webmaster 0]

Johnson Automatics manufacturing Co. had two Thompson automatic electric arc-welding machines that were installed at the Cranston plant for production of JSAR and LMG receivers.

The differences most likely are different set-ups on the two machines.