Saturday, February 23, 2019

Triggers and Owen sub-guns

This is about how a machinist would lay out the parts if he were going to cut them from 1/4", 1045 or 1137 steel bar with a 3/8", carbide mill. The use of a medium carbon steel facilitates the flame hardening of the sear surfaces to 55-to-60Rc.

My friend gifted me with the stock trigger from his AR after I installed his aftermarket trigger.

Three pieces, three springs. It is a very simple design.

The two biggest pieces are the trigger/sear in the top portion of the photo above and the hammer in the bottom of the photo. The original parts are both sintered metal in the model my friend bought.
Approximate orientation of the two pieces as assembled. The sear regions of both pieces are precision ground and the pivot holes are drilled but everything else is net shape. The third piece is not shown.

The third piece functions as a safety and to prevent auto-fire.

In thinking about the story, Seven Cows, I could see a time when a machinist might be tempted to knock out weapons to arm a militia. Given the limitations of the supply line and the retail prices of commercially manufactured components, he might be tempted to manufacture many of the parts in-house.
It hurts my eyes, especially the stock.  The Owen gun had extraordinary reliability as the spent shells ejected downward and the opening for the charging handle was in a separate compartment. That is why the receiver is so long.

He could do far worse than to modify an Owen Submachine Gun to accept commercially available magazines.
Line of sight two inches above the bore. Sighted in for 100 yards.

Since I have a hand in creating this parallel universe, I am pretty sure the machinist will rotate the magazine well 10 degrees to the right to put the sights two inches above the bore and he will probably put the stock more in line with the bore to minimize muzzle climb.

Oh, and the guns will need triggers. If he massed up the bolt to lower the rate of fire to 300-to-400 rounds per minute it would not be hard to launch single shots or two round bursts.


Increasing the length of the spur on the hammer would result in the hammer giving the trigger a little love-tap to return it to the not-fire position. It would take more finger strength to hold it in auto fire mode.


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