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Ar15/lr308 front takedown pin spring


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Same spring.  In fact, pivot pin spring and takedown pin spring are the same, AR-15 and .308 AR.  Same one.


In the pivot pin, it doesn't go all the way in - the detent sticks out.  You need to compress it with the pin, or compress it to get the pin in there.  It can be tricky.  Attempt to assemble it inside a 1 gallon zip-lock freezer bag - because when the thing shoots out, it won't go far... 


If you attempt to assemble it uncovered, and it shoots across your room - you will never see it again...

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It was way easier on my 15 everything went smooth, this one just wont compress down. I tried but then gave up becuase i started thinking of cerakote or some coat of some sort lol. I've been lucky to find the detent once or twice what i havent found is an old bolt catch pin lol

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Might be a "machining problem" on the lower, then, if that hole isn't the proper depth.  I don't have an unassembled lower on me right now, or I'd measure it for you - someone here has to have one, though.  It's gonna be the exact same depth on a .308 AR as it is on an AR-15 lower, so just about any lower should do for measurement... 


EDIT - Eff it, I've got a built lower that I'll strip down tonight...  I'll get a measurement back in here before the clock strikes 12...  I can take some additional pics, then, and show you how to get that thing together easier...

Edited by 98Z5V
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Could you be trying to install the stiff safety detent spring instead of the front pivot spring? The front pivot pin and rear takedown detent springs are the same but the safety detent spring is different. That is the one that fits in the grip. It is significantly stiffer than the other two springs but I think it is the same diameter and length.

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You can use a dill bit that's close to the spring hole dia. & just using your fingers , spin it in the hole & see if its got a burr or the depth of the spring hole is wrong or too shallow .

You can always cut the spring down if the hole is not deep enough.



I can beat you , I have a lower unassembled in the safe, but I know how much you want to disassemble that pivot pin, so I won't measure it .

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As fate would have it, that lower I have is locked in a gun locker - to which the key is on my Dodge keyring.  Which would be in Dawn Marie's purse about now.  At work. 




Never an issue when I was the only one that drove the truck...  :-[

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I would not make the spring hole any larger , the drill bit is just to take measurement & make sure the hole is clear of anything from machining marks or burr's .

I'll measure mine 98.


1.130" on my BRO lower, I used a straw from a spray lubricant , to take & measure . If you need the spring length , let me know ,I buy them by the ten's ,because so many lose them & its detent.


Can you see the spring in the oiling hole , for that spring , if it has it , some lowers don't , my CMMG doesn't .

Edited by survivalshop
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