Ar15 takedown pins

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"Loosen" them up? How do you suppose that pushing them in and out will loosen the up? Are you saying that either the pins are slightly oversized or the holes in the lower slightly undersized or both and the pins fit tightly into the holes in the lower or are you saying that the detents are difficult to over come? Or maybe a bad fit between the upper and lower?
 
There are some polymer wedges that are in stalled around the rear pin that are available that tighten up the fit of the upper and lower. I've tried some and am not sure if they improve accuracy.

For many rapid fire games, some looseness between the upper and lower probably does not make a difference. If accuracy is a must, it might be desirable for the fit between the upper and lower be a tight.
 
Thegreengiant34 said:
Is it bad to loosen up the takedown pins by pushing them in and out, ive done it quite a lot. Brand new build.
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Bad in what way? As long as they are not so loose they fall out the gun is still safe to fire.

I doubt how loose or tight it is changes the reliability of the gun, again unless it falls out.

It might change accuracy but I am not sure about that one way or the other.
 
I have no personal experience but have read numerous times that the slop does not affect accuracy. It would still bother me if there was a considerable amount and I’d probably go the wedge route.
 
I have noted that fresh anodizing is rough, and a bit of work polishing with oil eases things considerably.
 
I routinely stone the tips of detents to break them in.
I was an armorer for many years before I built my first one and I liked the way the old worn M16s had easy push pins.
 
GunnyUSMC said:
Simple answer, No.
The main thing that does wear is the detent pins. Just put a drop of oil in the channel in the takedown pins. This will help them last longer.
Oh! I have never worn out a takedown pin detent pin, ever, but I have launched a few into obit.
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I'm pretty much guaranteed to launch the front takedown detent pin into orbit every time I assemble a lower. Most of the times I do find it but I do keep a small parts bag full of extra pins and springs for when I can't find them.

As far as a take down pin wearing out, I can't say that I ever had to replace one or seen one replaced from normal use the entire time that I was in the Army. Rifles are kept in service for a long time and soldiers are constantly taking down their rifles to clean them.
 
Have to decide why the pin is sticky. Is the pin itself tight in the receiver bore(s)? Is it wedged due to poor fitment between the receivers? Or is it just the sharp edge of the detent recesses or an insufficiently beveled detent pin tip (straight wall of the pin contacting the detent recess).

The solution is different for each respective cause.
 
Takedown and pivot pin function are almost always going to be rough on a new build. It is metal on metal that hasn't seen use, so it's absolutely gritty at first. You're not hurting anything by breaking them in. Spring pressure forces the detent into the detent holes of the pin. Pins that are tough to disengage just need a very specialized tool that can be found in every loaded magazine. Guns with round counts in the multiple thousands may need oversize pins as the pin holes stretch, but the detent/pin friction does smooth out as the parts wear in.
 
cfullgraf said:
There are some polymer wedges that are in stalled around the rear pin that are available that tighten up the fit of the upper and lower. I've tried some and am not sure if they improve accuracy.

For many rapid fire games, some looseness between the upper and lower probably does not make a difference. If accuracy is a must, it might be desirable for the fit between the upper and lower be a tight.
Click to expand...

Eh, if you don't like the slop, just put an o-ring around the lug of the upper. That'll tighten up the fit.
 
So this photo with the wear around the hole isn’t a concern I am just worried that doing this has shortened the life of the lower.
 

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Thegreengiant34 said:
So this photo with the wear around the hole isn’t a concern I am just worried that doing this has shortened the life of the lower.
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Aluminum lower? Looks fine to me. I have one that is super sticky and I’m considering teaming it out with sandpaper so that I do t have to palmslap a screwdriver to get it moving.
 
I don’t know why some people worry about stiff takedown pins. Many will be stiff when new, but will wear in with use.
Get one of these for your range bag and your workbench. It will keep you from scratching the outside of your receiver.
https://www.midwayusa.com/product/1007038465?pid=811647
upload_2020-5-27_7-28-40.jpeg
 

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I lap mine quickly and only slightly with a steel mandrel when building, and then polish out the detent groove and end mortises slightly, as well as break a radius onto the corner of the detent cones. Secure detent lock, but the pins will push out with gentle thumb pressure. No reason to need any tool when 4 min of dressing work will create an ideal function.
 
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