[Fudgie Ghost]

Just got back from the range. While shooting my AR (not rapid fire), it didn't go boom once as I pulled the trigger. "***. . " I wondered as I looked down and around the reciever. As I took my arm off the forend, the upper and lowers hinged open!! Excuse me!? There on the bench was my takedown pin. Picked it up, looked at it. It was a bit "wet" with lube. Put it back in, and noticed that it was very easily pushed out.

So, was this just a case of too much lube in the gun making it too slippery? Do they make a two-piece take down pin like I have for a pivot pin, which prevents "walking"?

Or what?

Obviously this kind of thing could be very embarrissing---or deadly.

[ShaiVong]

The takedown pin in my AR is slotted so that a spring loaded detent can snap into the pin, holding it open or closed. Does yours just stay in via friction?:confused:

[Kharn]

IIRC (I dont have one nearby), the pin is supposed to have a little pocket in the detent channel where the detent rests when in the closed position so that its held in place very securely and not just by friction alone.

Where were the detent (little thingie about 3/32" in diameter, and about 1/4" long) and spring (about 3/32" in diameter, ~1" long)? The pin should have absolutely not fallen out if the detent and spring were in place (assuming the pin was rotated so the detent rode in the channel).

Is this an 80% lower (aka homemade) or a commerical one? What manufacturer, if its commercial?

Kharn

[cordex]

Agree with Kharn. Sounds like you lost your takedown pin detent and/or spring. Maybe last time you took off the stock?

[Mark Tyson]

It's possible the spring is still in and just bent. Similar thing happened to me, but not as drastic. All those little springs in there ... one thing I hate about the AR15.

[Fudgie Ghost]

Mmmmm. . . Well, I'm cleaning the thing as I write this, well not exactly at the same time, so I have the piece right in front of me. (By the way it's a Colt--all Colt--AR15 HBAR/A2) There is a slot in the pin, with what appears to be two very small holes (detents) at either end. Funny thing is, when this happened, I took a look at my buddies Bushmaster to see if there was something missing, and his pin looked just like mine(!). So I figured I wasn't missing anything. Sounds like I am. Will I have to get a hole new pin?

[cordex]

Ghost,
Remove the stock from your rifle (top screw on the butt)
Look underneath the right hand side of the buffer tube
Do you see a spring coming out of a small hole there?
Remove that spring and the rear takedown pin.
Is there anything left in the hole? There should be a little rod that will fit into that groove but it may not come out unless asked very nicely. Or it may fly out when you're not looking.

My guess:
You or someone else took apart your rifle to clean it, took the stock off and didn't reinstall the takedown pin detent and/or spring OR squashed the spring so it couldn't press hard enough..

Another possibility is that your detent has worn through the side of its hole and broken into the inside of your receiver.

I'd take pictures, but my batteries are on the charger.

Let us know what you find.

[Fudgie Ghost]

Cordex: Intresting that you should mention taking the stock off. . . I did change the collapsible stock back to the "stock" stock, a few weeks ago. At that time, when I took of the collapsible stock, I saw a plate, sort of a spacer, that had a spring coming out of the rear reciever into it---but this was on the horizontal plane, i.e., parallel to the stock. It didn't seem to be useful with the solid stock, so I taped it to the CAR stock and put it in a bag--it's with my extra AR "stuff". I didn't see any rod though.

Anyway, I just ordered the pin and the spring detent from Fulton. I'll take a look at the pieces from the CAR stock, and see what I find. Worst case, I'll have an extra take down pin assembly.

Thanks for you input--knew I could count on the THR brain trust!

[Kharn]

Fudgie:
Here's a pic to help you ID any small parts:
http://www.ar15.com/content/docs/assembly/lower/lowerKit.gif

And here's a pic and instructions on how to put the A2 stock on:
http://www.ar15.com/content/docs/assembly/lower/a2Stock.gif
A2 STOCK



--------------------------------------------------------------------------------
PARTS: takedown pin, takedown pin spring, takedown pin detent, stock, buffer extension, retainer, retainer spring, buffer, buffer spring
TOOLS: #10 (or larger) flat-blade screwdriver

--------------------------------------------------------------------------------


Insert retainer spring and retainer into recess in lower.
Install buffer extension, (buffer tube); press detent when necessary; torque to 35-39 ft-lbs add spacer onto stock tube, and insert stock.
Install takedown pin with groove to the rear and install detent and spring from the rear of the receiver.
Carefully compress the spring with the stock and secure the stock in place with the self-locking screw.
Insert stock screw from rear into stock.
With hammer down, insert buffer spring and buffer into buffer tube until retainer snaps up to lock it in place.
Function check on takedown pin and buffer retainer.

(All images and instructions borrowed from www.ar15.com)

Kharn

[techmike]

Just take a BIG GLOP of JB Weld and coat the pin really well. THat should do it:evil:

(Please don't do that and if you do don't blame me)

On a serious note...You can get Anti-walk pins that have a retainer-thingy(yes that is a technical term ) to stop the pins from coming out. I suspect however that you are missing a spring and replacing it should solve your problem.

[Fudgie Ghost]

Okay, need some help here guys. Got the new pin, spring and detend today from Fulton. (Hey are they a great company or what?) Looking at the exploded view and instructions posted here. . .looking into my lower reciever. . . looking back at the instructions. . . . ***?!

1. What goes in the slot on the take down pin?

2. The detent does not fit into the spring. Should it?

3. I cannot for the life of my figure out how the spring and detent will keep the pin from coming out. The very back "wall" of my lower is solid. No holes, slots, nothing. Are you supposed to jam the spring in between the pin and the back "wall" of the reciever?

Please hurry, S could HTF any minute, and I'd be as helpless as a soccer mom in Afghanistan.

[Kharn]

Hmmm, thats interesting.
There's no small hole on the back of the lower, like in this picture?
http://www.roderuscustom.tzo.com/cgi-bin/ib3/iB_html/uploads/post-11-51935-P4210002.jpg
You install it by putting the pin in place (aligning the slot so it points to the back of the lower), then dropping in the detent and then the spring into that small hole in the back, and then putting the stock on. The detent does not go inside the spring, they just sit with their ends touching.

Kharn

[cordex]

*grabs the bats for the digital camera and his AR*

[cordex]

Okay, lets give this a go.
Click on the images for a larger picture.

Takedown pin parts
http://24.208.209.169/images/creek/arTakedownParts_s.jpg (http://24.208.209.169/images/creek/arTakedownParts.jpg)

Step 1
http://24.208.209.169/images/creek/arStep1_s.jpg (http://24.208.209.169/images/creek/arStep1.jpg)

Step2
http://24.208.209.169/images/creek/arStep2_s.jpg (http://24.208.209.169/images/creek/arStep2.jpg)

Step 3
http://24.208.209.169/images/creek/arStep3_s.jpg (http://24.208.209.169/images/creek/arStep3.jpg)

Step 4
http://24.208.209.169/images/creek/arStep4_s.jpg (http://24.208.209.169/images/creek/arStep4.jpg)

[Fudgie Ghost]

Yeah, you know, this is another good reason why I have to get a digital camera. Care to donate the "Fudgie Ghost Digital Camera" fund?

Is that picture taken from the "shooter" side of the stock? Maybe I should remove the stock?

But no, looking into the lower, towards the buffer, I see no hole beyond the one for the takedown pin.

Hang on! Just looking at those thumbnails, and looking hard again at my lower--yeah I see raised channel on the outside and see where it will push detent out into slot/hole in takedown pin. I think I'm just missing the spring, so there's no pressure into the pin at the moment.

Boy is my face red! Oh well, there goes my chance for AR15 armourer of the year!

Thanks all---if you're ever in the NY metro area, I owe you a frosty one!

[cordex]

Yeah, you've got to pop the stock.

Sorry, I left that step out.

[Texas Gunman]

This is some very useful information posted here, plus pictures.:cool:
Im waiting on a CAR stock, going to install it myself, good to know these things mention above.

TG :)