[adirondack lightning]

My trusty US Postal Carbine, reliable pal of many years has recently started to fail to fully eject spent cases. the cases get stuck just above the magazine neatly jammed between top of the bolt face and the receiver ring. i stripped the bolt, tossed the parts in an utrasonic cleaner, and reassembled it with a new extractor and spring, ejector piston and spring along with a new op rod spring (Wolff kit from Brownell's). appropriate lube was used during reassembly. this did little or nothing to help. i tried different mags, and had the same result. so the question is am i "running out of gas"? the gas piston looks good and is free in it's bore, but i have never had the piston out and cleaned inside the gas block. i have a gas piston wrench, and am not afraid to go in there if that's where my problem lies. i thinking the gas block is filled with crud from cleaning etc and i'm low on pressure. any ideas on this?

 

[dfariswheel]

You've already eliminated the major suspects in the extractor and ejector assemblies.
Started using different ammo???

About all that's left is a binding op rod, or binding against the wood.

I'd be taking a careful look at the gas system.

If you're going to disassemble it, I'd go ahead and replace the piston and nut with a new USGI set. (Make SURE they're USGI not aftermarket).
Be VERY careful not to strip or cross thread the nut.

 

[ken k]

if you have never had the gas piston out it might be difficult, good advice above, order another spanner nut, spray the piston nut with gumout carb cleaner, do that a few times before you attempet to remove the nut, the gunout will loosen the carbon

 

[adirondack lightning]

i have been through a few boxes of assorted ammo and the commercial (Winchester USA or Remington UMC) was the poorest to eject. healthy Milsurp allways shot best out of this rifle, and ejects better, but back about ten years ago when i got this thing and for a good 7-10 thousand rounds until recently it digested anything i ever fed it with no problem. obviously something has changed. the op-rod is free, and does not bind on the wood or it's rails etc so i don't see any other cause than the gas system. i'll have to get a few piston nuts on hand for the job just in case i puke the old one. thanks for the adivce guys, and the new board sure works great!