Rear Pin won't move on AR-15. Can't separate upper from lower.

[Standard]

After installing a new rear plate for a sling, the rear takedown pin won't come in or out...do I maybe need a new spring and little pin that keeps it in place?
If it looks out, I can't push it in. If it locks in, I can't push it out...the gun fires perfectly...
I may have damaged the spring a bit when installing the new plate, if that can cause the problem, where can I get a new one?
Thanks for the help.

[supersonic]

PM sent.

[Crusader]

Try pushing it in harder.

[SJgunguy24]

Sounds like you need to clip a little off the spring.

[SJgunguy24]

Try pushing it in harder.

Thats what she said

[Standard]

Sounds like you need to clip a little off the spring.

I did, no help
I'm going to have to buy a new spring regardless, so I'll try clipping it some more.

[jlb]

my Bushy sits real tight on my LAR lower...I actually need a tool to push the pin out when I seperate for cleaning

I don't find it to be a problem...I actually like how tight it sits

[Vtec44]

Try pressing the upper down onto the lower receiver while pushing the rear take down pin out. I had the same issue this morning with a brand new AR and that's how I was able to get it out, Bushmaster upper with Superior Arms lower.

[Standard]

I'll give it another shot, I was trying every which way to get it out.

[Vtec44]

Or you can try to put it back but without the detent pin and spring, to see if that is causing the problem.

[MotoDuc]

I had the same problem, I replaced the detent and it's been fine ever since. If that's not it at least it was a cheap try.

[WallyGeorge]

Sounds like a detent issue. They are purposely soft metal and can get burrs/marred easily. After trying to move the upper and lower around while pushing the pin out like was recommended above, just take a dowel and tap the pin out. The detent will eventually work as designed.

[dchang0]

You might have forgotten to put in the detent and just put the spring in. And the spring may have gone into the detent hole and "locked" the pin in place. Take off the buffer plate and pull the spring back out in case this is what's happened.

[Standard]

The detent was definitely in. I took it all apart again, and it looks like the detent pin was slightly marred, so I flipped it around, cut the spring a bit where it was damaged, and now it works fine.
Thanks for help fellas.