Takedown Pin Detent Modification

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[ARCHIVED THREAD] - Takedown Pin Detent Modification

Posted: 6/4/2008 5:56:56 AM EDT

Anyone know where this thread went?

Posted: 6/4/2008 7:49:53 AM EDT

[#1]

I saved it to my home hardrive awhile ago. I am at work at the moment, but later this evening, I can dig it up and either repost or email it to you.

I've done the mod four times. It's pretty easy and works well.

You'll need a 4-40 tap, a 4-40 set screw and a .05 hex wrench.

IIRC, the set screw only needs to be about 1/8th" long. I've never been able to find them that short, had to cut down my own, then run it thru a 4-40 die to make sure the threads are clean.

Cut approximately 1/8th" off the spring (a couple of coils).

Hope this helps.

Posted: 6/4/2008 9:33:50 AM EDT

[#2]

If you can repost for the benefit to all, that would be great.

I have (SPF) a lower that I made this mod on and I'm failing at explaining what was done so that the buyer understands.

Posted: 6/4/2008 9:57:07 AM EDT

[#3]

Here ya go.

Retrieved from the archives --

Quoted:

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?

A 4-40 tap with a little oil... Sure wish tapping an AK trunion was this easy as Aluminum is easy!

Here is the tapped hole. Just blow it out with some compressed air when done tapping.

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 ).

1/8-inch 4-40 Allen head set screws. I got these at my local hardware for $0.10/each.

0.5mm Alen wrench. Note a handy wrench like this makes it easier to keep the spring from flying!

Set screw on the wrench.

Shortened rear detent spring back into the hole.

Screwing in the 4-40 Allen head set screw.

The head of the allen head screw with a standard AR-15 buffer tube.

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...

Posted: 6/4/2008 10:30:23 AM EDT

[#4]

Thanks!!!

Posted: 6/4/2008 3:01:12 PM EDT

[#5]

Great info. Thanks.

Can this also be used for the selector pin as well?

Posted: 6/4/2008 3:23:37 PM EDT

[#6]

No, not on the selector. There wouldn't be any room left for a spring on top of the set screw.

Posted: 6/4/2008 5:05:00 PM EDT

[#7]

I just did this. It was pretty easy, but I almost lost my rear detent spring several times while trying to install the set screw.

Posted: 6/4/2008 9:41:18 PM EDT

[#8]

Wow, this is great info. I wish I knew this a long time ago. It would've made installing Mapul 93s a lot easier.

Posted: 6/5/2008 7:19:11 AM EDT

[#9]

Yeah. It's one of those little things that make you say, "Why don't they come from the factory this way?".

Posted: 6/18/2008 7:07:40 PM EDT

[#10]

As a matter of fact, my Tactical Innovations lower did come like this from the factory. But does that mean that I will need to trim the spring as shown? Their website says to use all mil-spec parts. I sent them an email a week ago to clarify but got no response.

Posted: 8/18/2008 6:26:42 AM EDT

[#11]

bump

Posted: 8/18/2008 11:21:45 AM EDT

[#12]

Quoted:
As a matter of fact, my Tactical Innovations lower did come like this from the factory. But does that mean that I will need to trim the spring as shown? Their website says to use all mil-spec parts. I sent them an email a week ago to clarify but got no response.

Well it'd take all of 5 minutes to find out, eh?

Posted: 8/21/2008 6:30:50 PM EDT

[#13]

Fire1, Try this Email address. [email protected] I have never had a problem with getting an answer from Craig.

Posted: 8/23/2008 7:17:47 AM EDT

[#14]

Wow, Cool well I better get to work. Thanks for the great idea and the great pics. Hope you don't mind if I use this project. Thanks again

Posted: 9/2/2008 5:12:02 PM EDT

[#15]

What other sizes may be compatible? 6-32 may be a good fit.

What size set screw to use for the selector detent spring?

Posted: 9/2/2008 6:24:07 PM EDT

[#16]

We do this mod on every complete lower/rifle we sell. Well worth the time/money IMO.

Posted: 9/10/2008 8:36:49 PM EDT

[#17]

Nice! I'm definitely doing that to the build I'm working on now.

Posted: 9/10/2008 9:17:51 PM EDT

[#18]

Excellent mod.

Posted: 9/11/2008 3:09:50 AM EDT

[#19]

What a great idea

Posted: 9/11/2008 11:02:04 AM EDT

[#20]

all lowers shoud come that way .

Posted: 9/13/2008 4:46:37 AM EDT

[#21]

Got to try this, thanks.

Posted: 9/13/2008 6:25:28 AM EDT

[#22]

Sticky this with the "How-To" thread.

buckmeister

Posted: 9/13/2008 4:33:04 PM EDT

[#23]

This mod is so easy its ridiculous. Went down to Ace Hardware and got all of the tools and pieces for less than $15. Less than 5 minute mod once the stock/ receiver extension is off. Probably around 10 minutes from breakdown to reassemble if the receiver extension staking isn't a problem. Excellent post and big thanks to Quarterbore and Osprey21 for the how-to info.

Posted: 9/14/2008 6:28:10 AM EDT

[#24]

Well good luck finding the materials needed.

I had to go to 4 diff. places just to find the 4 40 tap.

Ive got to go to a Hobby store to get the set screws. HOme deblow and Lowes only go down to 6 32. I did get the tap from Lowes.

Posted: 9/14/2008 12:02:35 PM EDT

[#25]

Quoted:
all lowers shoud come that way .

I don't know if Spike's Tactical is doing this to all lowers but the last one I received had the conversion done. There was a mix up at Spikes and "my" lower had been built up but since I did not want the FCG and grip they used, they removed those parts and I agreed to take the other parts that had been installed. When the little bag of parts did not include a rear take down pin spring and detent I figured WTF, where are they, then I noticed the set screw. Good enough for me. I hope they are doing that to all their lowers and if not, they should as should everyone else. This is one of those conversions that you just smack yourself on the forehead and say, "Why didn't I think of that years ago?"

When I did my other 15 or so lowers I got the tap and bit from the local ACE hardware store. I got the 4-40 x 1/8 screws off the net and IIRC it was one of the e-Bay stores. Something like $10 for 100 cup point set screws. That should last a while.

Posted: 9/14/2008 12:53:15 PM EDT

[#26]

Quoted:

Quoted:
all lowers shoud come that way .

I don't know if Spike's Tactical is doing this to all lowers but the last one I received had the conversion done. There was a mix up at Spikes and "my" lower had been built up but since I did not want the FCG and grip they used, they removed those parts and I agreed to take the other parts that had been installed. When the little bag of parts did not include a rear take down pin spring and detent I figured WTF, where are they, then I noticed the set screw. Good enough for me. I hope they are doing that to all their lowers and if not, they should as should everyone else. This is one of those conversions that you just smack yourself on the forehead and say, "Why didn't I think of that years ago?"

When I did my other 15 or so lowers I got the tap and bit from the local ACE hardware store. I got the 4-40 x 1/8 screws off the net and IIRC it was one of the e-Bay stores. Something like $10 for 100 cup point set screws. That should last a while.

I finally got my 4-40 set screws from hobby store. I got the tap for 5bux and the screws for 2.00 for 10. So ive got 7bux plus the gas to get them. lol

I agree that this is one those mods that shouldve been done from the factory and a long time ago.

Posted: 9/14/2008 4:28:48 PM EDT

[#27]

Got everything at Ace Hardware. The tap handle was like $6.00, the 4-40 tap bit was close to $5.00, the 4-40 set screws were .11 cents each. Already had a hex key and oil.

Posted: 11/19/2008 5:48:28 AM EDT

[#28]

bump

Posted: 11/22/2008 12:09:53 PM EDT

[#29]

linked from mr0w1's 'fustrated picture thread' contribution.

Posted: 12/22/2008 8:59:03 AM EDT

[#30]

bump

Posted: 1/8/2009 8:05:26 AM EDT

[#31]

Is it just me or does the set screw look identical in size to the set screw you put into the ram on a dillon 550

If one was dishonest he could "lose" that screw then dillon send a freebie. Just sayin they look the same

Posted: 1/8/2009 12:27:49 PM EDT

[#32]

Quoted:
Is it just me or does the set screw look identical in size to the set screw you put into the ram on a dillon 550

If one was dishonest he could "lose" that screw then dillon send a freebie. Just sayin they look the same

They cost a nickle or 10 for 2.00. how much of a tightwad are you really.

Posted: 1/8/2009 12:28:48 PM EDT

[#33]

good stuff. thanks QB.

Posted: 1/8/2009 2:50:02 PM EDT

[#34]

I've done this to 4 lowers, works great and is how it should have been. Just cut your spring no longer than the set screw if not a tad shorter and you are styling. It just too stupid easy.

Posted: 1/14/2009 4:26:22 PM EDT

[#35]

This mod seems like a total waste of time. I mean what really is the point?

Posted: 1/14/2009 6:18:09 PM EDT

[#36]

Quoted:

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...

From the original thread for this mod.

Posted: 1/15/2009 7:15:15 AM EDT

[#37]

Quoted:
This mod seems like a total waste of time. I mean what really is the point?

Cheap insurance. Keeps your gun from being down for an indeterminate amount of time from a lost part and not having spares. Hard part to find depending on where you are when the detent launches itself.

Posted: 1/16/2009 5:59:25 AM EDT

[#38]

Quoted:

Cheap insurance. Keeps your gun from being down for an indeterminate amount of time from a lost part and not having spares. Hard part to find depending on where you are when the detent launches itself.

The Detent is behind the spring so not sure how the detent is going to launch itself.
I see how some people have problem with the pivot pin detent and spring, but not the take down.

Are people changing their stocks that often?

I only build a dozen or so lowers a week, but I can not remember ever having an issue with the rear spring.

Posted: 1/16/2009 10:22:46 AM EDT

[#39]

I got the tap and about a dozen set screws at our local hardware store yesterday. Thanks for the good idea!

Posted: 1/16/2009 10:23:46 AM EDT

[#40]

Quoted:

Quoted:

Cheap insurance. Keeps your gun from being down for an indeterminate amount of time from a lost part and not having spares. Hard part to find depending on where you are when the detent launches itself.

The Detent is behind the spring so not sure how the detent is going to launch itself.
I see how some people have problem with the pivot pin detent and spring, but not the take down.

Are people changing their stocks that often?

I only build a dozen or so lowers a week, but I can not remember ever having an issue with the rear spring.

You are correct sir. My error. Can only speak for myself but have moved or replaced stocks on better than a half dozen and have launched a spring or two. Got smart and started having extras ready but remember a gun being down for a while waitng on a .75 cent piece being delivered by mail. Guess if you do it often enough as a living you are not prone to this mistake too often.

Posted: 1/16/2009 1:49:09 PM EDT

[#41]

Quoted:

Quoted:

Cheap insurance. Keeps your gun from being down for an indeterminate amount of time from a lost part and not having spares. Hard part to find depending on where you are when the detent launches itself.

The Detent is behind the spring so not sure how the detent is going to launch itself.
I see how some people have problem with the pivot pin detent and spring, but not the take down.

Are people changing their stocks that often?

I only build a dozen or so lowers a week, but I can not remember ever having an issue with the rear spring.

So none if your 144 ish customers from the last year have asked for replacement or spare parts? You got the lottery #s too?

Posted: 1/17/2009 8:06:28 AM EDT

[#42]

Say the tap breaks in spring hole?
Mine did......

Its an SBR too.

I guess that KNS takedown pins are the only choice.

Posted: 1/17/2009 12:41:31 PM EDT

[#43]

Quoted:
Say the tap breaks in spring hole?
Mine did......

Its an SBR too.

I guess that KNS takedown pins are the only choice.

You could try to get it out with a Tap Extractor

Example

They can be bought from McMaster Carr

Posted: 1/17/2009 12:54:01 PM EDT

[#44]

I've done the mod on most of my lowers and it's terrific thing.

I'm going to try to do something similar to the damned buffer detent and spring.

If anybody can think of a way to tame the selector spring, please post!

Posted: 1/17/2009 3:46:09 PM EDT

[#45]

Im going to have to get one of those tap extractor sets.. it will save so many scrapped parts of mine.
I am king of breaking taps.

Once I get the tap out, I wont stick anything in there ever again

Posted: 1/18/2009 6:33:47 AM EDT

[#46]

Quoted:
So none if your 144 ish customers from the last year have asked for replacement or spare parts? You got the lottery #s too?

200+ a month since October :D

I do have a number of people buy spare parts, but its probably <5 a month.

I guess I have just never known someone that changed their stock out all the time.

So offering this as a 10$ option would be a good idea?

Are people loosing buffer retainers also?
I can see doing something similar there.

Posted: 1/18/2009 6:50:26 AM EDT

[#47]

If your breaking taps your going way too fast, applying too much pressure too soon, not using enough oil and not removing and cleaning the tap enough times as you go.

A little in, then out, clean & oil and back in then out, repeat....

Posted: 1/18/2009 7:03:08 AM EDT

[#48]

Great thread. Great idea.

Looks like I'll have something to whittle at while watching the games today.

Posted: 1/19/2009 5:44:39 AM EDT

[#49]

Wel the links to the tap ex-s, their cost is 100$ minimum order and each tap set is $36.

I am just leaving the tap in there and using KNS pins until one lucky day when I help M60Joe change a flat tire in the rain on the side of the road and he owes me a favor.

Posted: 1/19/2009 5:23:08 PM EDT

[#50]

Quoted:
Wel the links to the tap ex-s, their cost is 100$ minimum order and each tap set is $36.

I am just leaving the tap in there and using KNS pins until one lucky day when I help M60Joe change a flat tire in the rain on the side of the road and he owes me a favor.

You can order individual tap extractors at McMaster Carr. I posted a link to there site also. You can search for them at the link

[ARCHIVED THREAD] - Takedown Pin Detent Modification

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