Carbine piston doesn't move

[Benny]

I have a National Postal Meter carbine that I have fired several times When I take it apart I notice that the piston doesn't move . I have tried soaking it, hitting the housing with a rubber mallet and it still doesn't move, BUT it works. Is this something I should be concerned about? I only have fired 2 rounds each time and it works just fine.

[bonnie]

If I understand correctly you only fire two rounds through it each time but have done so several times?

Why not run several 15 round magazines through it at one setting to confirm it functions properly? Maybe a drop of bore solvent before shooting. If it works it should be good to go and nothing to be concerned about.

Piston removal requires a piston nut wrench to fit the piston nut. Removal and installation of the nut must be done carefully, so as not to strip the fine threads. If the nut is staked in place (military) it makes removal a little more difficult.

[Dan Shapiro]

BTW, the actual "movement" of the piston is only about 1/16".

[Tuna]

There is no problem with something that works when you use it. But a good cleaning, lubricating including the piston and then firing more then just two rounds at a time. Put a couple of magazines at least through it. Then you will know if it works OK or not.

[Benny]

Thanks Tuna: I'll try more rounds, I usually shoot in my basement into a 28"' dia. tree trunk , when my wife is gone. Next time I go out to the country I'll try a full mag.

[Sunray]

A 28"' dia. tree trunk will quickly fill with bullets and cause riccochets. Mucho dangerous. Worse if it's not hardwood.
There's no spring under the piston. Nothing to move. And Rule Number One. It works, don't fix it.
Piston nuts usually break when removed, even with the proper tool.
There's a free .pdf of the Carbine manual here. Note the need for the provided UN & PW.
http://www.biggerhammer.net/manuals/

[bonnie]

A 28"' dia. tree trunk will quickly fill with bullets and cause riccochets. Mucho dangerous. Worse if it's not hardwood.
There's no spring under the piston. Nothing to move. And Rule Number One. It works, don't fix it.
Piston nuts usually break when removed, even with the proper tool.
There's a free .pdf of the Carbine manual here. Note the need for the provided UN & PW.
http://www.biggerhammer.net/manuals/

Never heard of piston nuts usually breaking, even with the proper tool?
Have heard of some guys being careless and cross threading the nut. Never seen it.
GI's were authorized to remove the piston nut under direction of the unit armorer.
I've removed/installed a few over the years and never had an issue.

[jimb]

If not installed properly you could crack the cylinder then the barrel was scrap. The proper tools included not just a castle nut wrench but a threading tool for removing the staking on the side of the cylinder.

[Major Tom]

YIKES! Shooting in your basement at a tree stump? That should shake the dust from the rafters. 8-)

[free1954]

.
http://www.biggerhammer.net/manuals/

thank you sir for that link