Rear Detent fix.

[combatvet]

All credit goes to Quarterbore

I've performed this mod on all off my AR's and it is the best thing since sliced bread. All credit goes to Quarterbore from TOS. I think it should be stickied!


As posted from TOS:
In a thread in the EE I saw a number of people asking for the rear plate that retains the rear take down detent spring retained when using an AR-15 pistol buffer. To be honest, I got tired of fighting with that stupid little spring with my own AR-15 pistol years ago and I thought other people knew the simple trick to tap the rear takedown detent hole and then use a small allen head screw to retain the spring. Well, in case nobody has seen this done I decided to do this to a brand new lower I bought this weekend and my local fun show...

First, the rear takedown detent hole in case someone is asking WTF is he talking about?
http://www.quarterbore.com/images/ar...ingfix-001.jpg

A 4-40 tap with a little oil... Sure wish tapping an AK trunion was this easy as Alluminum is easy!
http://www.quarterbore.com/images/ar...ingfix-002.jpg

Here is the tapped hole. Just blow it out with some compressed air when done tapping.
http://www.quarterbore.com/images/ar...ingfix-003.jpg

Need to cut about 1/8-inch off the rear detent spring. If you don't do this when you tighten up the allen screw the spring will compress to the point that the detent will not come out of the divets in the rear takedown. (If you don't cut your spring, you will see what I mean ).
http://www.quarterbore.com/images/ar...ingfix-004.jpg

1/8-inch 4-40 Allen head set screws. I got these at my local hardware for $0.10/each.
http://www.quarterbore.com/images/ar...ingfix-005.jpg

0.5mm Alen wrench. Note a handy wrench like this makes it easier to keep the spring from flying!
http://www.quarterbore.com/images/ar...ingfix-006.jpg

Set screw on the wrench.
http://www.quarterbore.com/images/ar...ingfix-007.jpg

Shortened rear detent spring back into the hole.
http://www.quarterbore.com/images/ar...ingfix-008.jpg

Screwing in the 4-40 Allen head set screw.
http://www.quarterbore.com/images/ar...ingfix-009.jpg

The head of the allen head screw with a standard AR-15 buffer tube.
http://www.quarterbore.com/images/ar...ingfix-010.jpg

So, what does this do for me? Now I can remove my A2 Stock and add a CAR stock with no wories of bending or losing that spring. With my AR-15 pistol, it makes it so that I don't need to use the rear cover plate. If I want to replace the spring for any reason, I just unscrew the set screw and cut off another spring and drop it in there...

This is a 10-minute job and one I like to do on ARs that I swap stocks around on...
All credit goes to Quarterbore

Pictures added:
All credit goes to Quarterbore












All credit goes to Quarterbore

[Adam]

I don't think this is one of those things that needs fixed. I put the stock on my lower stake the castle nut on and thats the end of it.

[Stickman]

Did you ask him to repost his article and pictures? While he seems like a good guy, some people take offense to their articles being copied, instead of a link being given to it. Just a thought.

On a side note, its an interesting mod, but not one I see me doing to any of my weapons.

[combatvet]

Did you ask him to repost his article and pictures? While he seems like a good guy, some people take offense to their articles being copied, instead of a link being given to it. Just a thought.

On a side note, its an interesting mod, but not one I see me doing to any of my weapons.

I ensured ample credit was given. I see no harm in reposting what is already on the internet. But if I had his email I'd be happy to ask him personally. I respect your opinion Stick I just wanted to let others see this.

[Dan Carey]

The detent spring modification has been around for quite some time. It has been linked to on several sites.

[Razorhunter]

Is this something that is only done on AR PISTOLS????
Does my Colt M4 have this spring????
I have never even seen this spring before, and I have no idea what it's even for??
Thanks for any insight...

[Adam]

Is this something that is only done on AR PISTOLS????
Does my Colt M4 have this spring????
I have never even seen this spring before, and I have no idea what it's even for??
Thanks for any insight...

It's the rear detent spring (it holds the rear push pin in place). There on all ARs.

[Razorhunter]

Sweet, I gotcha. I've never had that plate off my rifle before. Makes perfect sense though.
This is a cool little mod, and it's definitley worth doing. so easy to do, and takes only a minute...
I'll have it done in 60 seconds...

[Adam]

If you've never taken the receiver plate off, why do you feel the need to do this modification?

[Razorhunter]

I don't feel the need to do anything.
I just think it's a great mod, and WHEN I DO start taking off the plates on other builds I do in the future, I'll grab a tap and thread the hole in a snap. Firearms and machining/gunsmithing are enjoyable to many of us.
It's called tinkering, and many of us on this forum like to tinker with our guns. We don't really need reasons...