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Old June 5, 2018, 06:53 AM   #1
Liberate80
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Join Date: October 18, 2017
Posts: 17
DIY Binary Trigger

A binary trigger for AR15 that does not have select fire and only has safe and two shots, you must fire both rounds. Once the trigger is pulled you have to release the trigger to put into safe. This is the first version, garage version, of what later became the BFS.

The flat of the selector where the back of the trigger hits the selector in fire mode needs to be dremeled out 3/16 inch. This allows the trigger to pull further back and causes you to slow your trigger pull timing. Pulling the trigger too fast causes a hammer follow and you have to rack the charging handle and waste a round. The hammer follow does not cause a slam fire.

The trigger needs to have a channel 1/16 inch cut on each side of the trigger just forward of pin hole lug mounts, where the top flat of the trigger meets the cut out for the disconnect. Wrap a medium, or small with sheathing, paperclip around the trigger once, cut to length, so that the front tip of the disconnect rests on top of the paper clip, the paper clip being held in place by the channels on the side. This keeps the disconnect pushed back.

The disconnect needs to be dremeled starting at the pin hole and going back toward the end past the spring pocket, 0 to 1/8 inch. So, starting at the bottom of the disconnect at the pin hole, 0 inch, draw a staight line to the back crossing the spring pocket, 1/8 inch up from bottom of rear of disconnect. Then dremel the spring pocket also about 1/8 inch deeper. This allows the disconnect to be pushed back by the paperclip and the spring to still work.

To shoot normal again just remove the paperclip.

This came from an old post from the BFS creator where he said he used a dremel for his prototype.

When assembled, with the trigger pulled back, make sure you have a good contact overlap where the disconnect meets the rear trigger catch. A very small overlap is not good. If the overlap is too small, dremel out the selector pocket more, or, your paperclip is too thick.

Good luck and have a lot of ammo on hand. I got rid of it and went with a Velocity trigger. Great trigger and doesn't waste ammo.

Last edited by Liberate80; June 5, 2018 at 06:45 PM.
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