I just resently picked up a Norinco preban in .223. It had an m16 type flash hider on it and I was thinking of changing it. I pushed the flash hider spring pin down to unscrew the flash hider and now the pin wont pop back up into place. I sprayed with WD40...oiled it(from the top) and it still wont pop up....any suggestions? Im getting pissed.

Brass hammer or platic mallet treatment may be called for....seriously...those two won't hurt your rifle they way a steel hammer would.  Might just need a little tap to reseat itself.

Try some gunscrubber. Oils and solvents just seem to make the problem worse.
Go easy with the gunscrubber(brake cleaner will do), it won't take much.

Im gonna take it out and shoot it  and see if that might dislodge the damn thing. Anyone know where theres a drawing or schematic of the front site setup with the plunger set up???? Campy I think I'll use your way as a last resort. I hate like hell driving pins out and back in.

Whack it on the side of the muzzle with a brass hammer to get its attention. If that doesnt work, spray in some gun scrubber or degreaser. Then whack it again. Its just being ornery. Show it who is boss!

Here is a sketch I made of the front sight muzzle brake retaining pin. Note the slot in the pin to clear the front pin that holds the front sight on the barrel so it can move. Sounds like you have some gunk or a burr on the pin keeping it from sliding freely. Knocking the front sight retaining pin out will allow the mbr pin to come out so you can clean it and check for burrs. I have run into the same problem on a NHM-90 rifle. There was a burr where the slot had been filed into the pin. A couple file strokes cured it.
http://www.gunsnet.net/album/data//500/966MBR-med.JPG

JA545, Thanks. Im going to shoot the gun in a couple of dyas. If it doesnt come loose I'll try what you suggested.

Maybe the spring inside is broke?

SUCCESS...I got it. I used JA545 suggestion and took the front pin out of the sight. I could just bareley see the end of the detent cap. I used a punch and drove it a little deeper than sprayed WD40 on the top of the hole and inside where the pin goes. I used a really small flat tipped screwdriver and put it in behind the detent the drove the screwdriver thru. The detent poped up. I pushed back down and let it up about a dozen times and its working like it should.  Anyway thanks for the drawing and clue on how to get it going again JA545. It was a pretty simple fix to boot. I dont think I'll have that problem again. I know it was minor but crap like that just drives me nuts. If everything is not working like it should I gotta fix it or else. Thanks everyone for your input. M4_Aiming_at_U, altho I didnt see the spring I dont think its broken. Its working like it should now. Probably some gunk binding it is my guess.

Thanks campy, after looking at the gun again I figured it had to the front pin like JA545 said.  What a relief on my mind LOL.