Detent stopping rear takedown pin..

[DS94901]

For some reason my most recent AR build is giving me a little trouble. When everything is put together, I'm unable to remove the rear takedown pin. I've tried 2 different detents and both end up a bit mangled on the tip which leads me to believe that the hole the detent slides into is too deep. If I release nearly all pressure on the spring, it functions normally.
Should I buy a new selector? Trim down the spring to reduce pressure? File down the tip of the detent?

[DS94901]

I meant new takedown pin, not selector.

[ar15barrels]

Knock the sharp tip off the end of the detent and it will not engage the takedown pin as much.
It's normal to have to knock the pin in and out of the lower a few times when new.
This is breaking the sharp edges that make the pin harder to move by hand.
Once the sharp edges are worn down, you will be able to move the pin with finger pressure alone as long as the pin is sliding freely through both receivers.

[xfer42]

Can you take a picture of the groove on the take down?
I suspect it has a sharp edge near one of the holes.

Make sure you grease it up.

[Gunsmith Dan]

I have had a few customers with kits that did the same thing for 2 different reasons.

1 customer the take down detent springs were to long and putting to much pressure.

the other 2 customers the detents were to long and almost a needle point on the ends.

If the points are not to sharp you can always file down the side toward the spring almost flat as well.

[DS94901]

I'll try filing the detent down a bit first and see if I can get the pin sliding. Thanks guys.

[ar15barrels]

I'll try filing the detent down a bit first and see if I can get the pin sliding. Thanks guys.

You don't even need to file it.
Just assemble everything, then use a punch to move the pin back and forth to the ends of it's travel a few times.
Those first few times going in and out of the detent holes will soften the edges of the detent.

[DS94901]

I think my last message didn't post. Just popped the takedown pin in and out three times with a punch and its working perfectly now. Thanks for the quick fix ar15barrels.