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Sonjohn

How the Johnson works?

4 posts in this topic

I understand how an M1 Garand works, some of the gas from the shot cartridge is bled off through the barrel to the gas port which pushes a piston/sprung op rod, which ejects the spent cartridge then feeds a fresh bullet from the en bloc clip.

How does the system work with the Johnson 1941 Rifle?  

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The Johnson design is known as "short recoil".  The barrel is not fixed to receiver but moves back about 3/8"upon firing.  As it and the engaged bolt move rearward, the bolt is rotated by a groove in top of receiver which unlocks it from the barrel.  Because there are 8 lugs instead of two, the bolt only has to rotate approximately 20 deg to unlock, then momentum carries the bolt (with extracted shell) back where the case strikes the ejector (pivoted on left of receiver) to throw case away.  Meanwhile the barrel has moved forward by action of the spring of the barrel latch.  As the bolt strips a new shell and comes forward, the receiver groove rotates the bolt and locks it into the 8 slot rear lug of barrel, ready to fire.  If you have a Johnson, push the barrel back and watch bolt unlock by rotation.  If necessary, the gun can be used as a bolt action by manually lifting bolt and retracting it.  The multi-lug bolt design has moved into many modern firearms.

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Correct on the use of the Johnson multi-lug bolt system. When Dad worked with Armalite in the 1950's on the AR-10 series, his bolt design was utilized, and the style of the AR-10 was patterned in appearance to the 1941 JLMG. Later, the M-16/AR-15 adopted that same bolt design and overall appearence. Thus, the M-16 is the "grandchild" of the Johnson SAR & LMG. As Joe indicates above, others later adopted that bolt design. Much of this is mentioned in the Bruce Canfield book "Johnson Rifles and Machine Guns" with info our family provided via myself in co-operation with research by Robert Lamoreaux. The book was initially published by Mowbray in 2002 and is in its 2nd printing.

 

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