Compliant Magazine Removal

[mtcjayne]

This is an idea for compliant magazine removal where a tool is required and the receiver my be open in an AR platform.

A through hole is drilled from the top of the receiver and partially into the magazine release button. "A" is a threaded, hollow cylinder in a tapped portion of the through hole. The inner diameter is large enough for a punch to be inserted but smaller than "B." "B" and "C" are pins that can move freely vertically but are retained horizontally by the unthreaded portion of the through hole mentioned earlier. "B" and "C" are limited in their upward and downward motion by "A" and the magazine release shaft. By default "C" prevents the magazine release button from being pressed to release the magazine. However when a punch is inserted through "A" and pushed down the gap between "B" and "C" lines up with the gap between the receiver and the magazine release button and allows the button to be pressed. "D" is a spring which returns "B" and "C" to their default position.

This is the way pins work in a lock.





Modification and Installation:

1. Drill through hole with magazine release button in place and not depressed
2. tap upper portion of hole
3. drop long pin B into hole
4. thread retainer A into hole
5. flip reciever upside down
6. partially remove magazine release button
7. drop spring D and short pin C into magazine release button
8. while holding down short pin D reinstall magazine release button
9. allow short pin D to click into the through hole
10. function test by ensuring magazine releaee button cannot be pressed unless punch is being inserted into hole in retainer A

What do people think of the idea? What would you as a gunsmith charge for this service if provided with the parts?

[mtcjayne]

As a built in feature screwing the retainer A deeper than normal will permanently enable the magazine release button, until the retainer is backed out again.

[Lonestargrizzly]

So you have to pick a lock in order to change your mag?

[mtcjayne]

Yeah, a single pin lock basically. Push and keep pushing mag release, push pin until mag release gives.

[Justinoff]

Isn't that what a bullet button is essentially ?


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[mtcjayne]

A bullet button is accessible without disassembling the weapon.

[Justinoff]

Isn't this?


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[kcstott]

Isn't this?


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ah no... look at the design

[canid]

Having explored various compliance methods also, I must say I like this.

You thinking of prototyping it? I won't be able to build anything any time especially soon or I'd be happy to give it a go.

[mtcjayne]

I don't think I'll be able to prototype it on an actual weapon, but it can be done by handby just about anyone which I like.

[canid]

You will find you are limited to about 8-32 for your insert part 'a' if you want to do it conveniently by hand (will still have to drift out the bolt release if it is installed or you would have to go down to something like 6-32. Anything bigger and it will be hard to start the hole in the required position due to the bolt release slot. The use of a mill with a plunge cut would make it trivial, or make it easier to come in from another angle but I think you want to keep it more diy friendly, yes?

I'll mock something up with some scrap stock if I get the chance.

[mtcjayne]

Yeah I was thinking last night that making part A hollow for a punch probably adds unnecessary complexity and cost.

[canid]

Not too bad, as long as the builder has use of a drill press, a suitably small diameter drill and I don't think I'd want to do that hole without center punching it.

It would be handy if that insert (externally threaded bushing? what would you call that?) is a standard part which could be purchased. My tiny little lathe is probably my favorite investment in my life.

[mtcjayne]

The key pins I have seen to be within the diameter limit here. The maximum length I have is about 5/16.

[canid]

You know, if you used a phillips head machine screw like one I'm looking at right here you could just screw it down into a tapped hole in some scrap stock (so long as the hole is drilled and tapped straight) and use the phillips head as a pilot for drilling. Then you just have to cut or grind the head away and you have your part, though you should probably slot it for installation/removal. You could also use a blind grub screw as long as the through hole is smaller than the allen socket. The later would also probably allow easy piloting for the through-drilling. Either way, anybody could do that on a drill press.

[6-32 screw, 1/16 drill]