AR15 Pivot Pin detent spring & plunger

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dburkhead

New member
I am beginning to curse Eugene Stoner and his descendents unto the 7th generation. I simply have not been able to get that detent spring and plunger into place and have spent more time crawling on hands and knees trying to find them after they've flown across the room than should be allowed by law.

The kit started with two springs and two plungers that were, so far as I could tell, identical. One is apparently completely lost while I've been able to recover one to try again. I suppose I could be finding both of them in turns and there's no real guarantee that the one I most recently found is the one I most recently lost. In any case, I've got one in hand and the other may turn up later to a more thorough search.

I'm working from a DPMS stripped lower and a parts kit from I don't know where (Friend of mine bought them for me). Is it possible that there's actually a fit issue (spring plunger combination a bit too long for the hole in the receiver) or am I most likely just proving incredible inept at this? If it helps, I have not been able to push the plunger down far enough to completely clear the hole for the pivot pin. At best it protrudes a bit.

Any suggestions?
 
I used a utility knife to assemble mine. It took about 25 minutes to assemble the lower. That counts about 10 minutes looking for the spring and detent that shot across the room.

Turn the knife on its side. Slip it between the spring and pin. Firmly, but carefully depress the spring while feeding the pin. There's even a segment on Youtube showing the same thing(which I found *AFTER* putting mine together).
 
In another forum, an individual said that they had had problems with fit in the past with DPMS parts, specifically that the spring/plunger combo was a bit too long. In their case they had resolved the problem by clipping 1-1 1/2 turns from the spring.

On the "what have I got to lose" principle, I tried the same thing on mine. Went in without a hitch.
 
Be careful with spring clipping. It may be the right solution here, but I always remember the original Garand rear site windage knob had to have a lock on it because the coil spring originally used would bounce on firing, causing momentary looseness of the adjustment which would shift. Bounce is much less likely in the low-recoiling AR, and may not be critical with the pin, but we don't want anything falling apart during firing, so have a spare spring on hand and test the assembly well afterward.

Let me add for those not familiar with navigating You Tube, that part II of the video Chadwimc linked to is http://www.youtube.com/watch?v=jq4KfUaVp8M&feature=related, if you want to see the complete assembly?

Since the technical solutions have been offered already, I just wanted to add my method of avoiding losing loaded springs and related parts. I just cut armholes into the side of a cardboard box and cut the lid flaps off the top. I picked up a sheet of plastic window glass replacement at Lowe's that I could lay over top of it and I just let gravity hold it in place. All the cardboard box lacks is a built-in light bulb. I don't find I really need one most of the time, but when I did, I just cut a small hole in the back of the box to stick an LED flashlight in.

The LED camping lights are getting cheap enough that I suppose one of those might be a good choice to put in the box if more light were needed? If you got really ambitious, you could use the plastic sheets to make the whole box like a giant cake box cover. Just set it down over your tools and parts on the bench and plenty of light would get in. I've been too lazy to bother.
 
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