M14-What causes case to jam in chamber?

Sharkson

Sharkson

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I have a usually very reliable M305 Norc, shortened to 18.75" by Valley Gunsmithing some 3 years back. Nice work.

Twice during my last shooting session with surplus 7.62, a fired case became stuck in the chamber. The first time I managed to pull hard enough on the op rod handle to get it open. The second time I had to take it home and "help" it open with my cleaning rod down the pipe.

Both pieces of brass don't look more beat up than normal.

I didn't unfortunately get a chance to try some commercial 308 ammo I have. It fired fine previously though.

Any thoughts??
 
You may be having a issue with "Short Stroking". This is were the fired round is extracted, but not ejected from the receiver due to a short extraction stroke. This causes the spent and expanded cartridge case to be forced back into the chamber and jammed in placed by the bolt returning to battery.
I would clean and grease the weapon, make sure that the gas port in the barrel is clear, make sure that the gas cylinder nut is tight. clean your chamber thoughly. Also try different ammo to see if it may be ammo related.
 
Was the surplus ammo a steel case? If so, what happens is the lack of obturation with the case wall. It fires, expands, seals gas but doesn't shrink and release from the chamber walls. Thats why brass is a better material than steel. It will shrink back until it gets worked over time (with reloading) that the case will eventually fail after many reloads. The steel s**t is usually berdan primed(two flash holes in the bottom). So you just toss it.
 
Mine does this as well. Approx 1 round in every 100 sticks in the chamber after firing. Near impossible to remove with out using a short piece of 2X4 on the op-rod handle. Mostly using SA and Norc ball ammo. I don't recollect it happening with factory or reloads.
 
Any grease or contaminants on the outside of the cartridge cases can cause a failure to extract. Can be alot like glue.

Jamiejaf is sort of correct, steel cases do have a tendancy to stick but not because of a lack of obturation. In rifles, Obturation is the sealing of the chamber by the expansion of the case. Steel has a tendancy in hot chambers too not cool rapidly enough to extract reliably in a semi.
 
Petrock said:
Any grease or contaminants on the outside of the cartridge cases can cause a failure to extract. Can be alot like glue.
Click to expand...

The last time this happened to me was after firing approx 70 rounds of SA ammo from a clean rifle. Out of the blue a stuck casing. Had to excuse my self from the competition to retrieve my 2X4. No issues for the rest of the comp.

The SA ammo comes boxed and is pretty clean as far as I can tell.

So what gives?
 
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I recently purchased a M305, and noticed in the manual it warns against using ammo with soft primers; (issues with slam firing). What brands of factory ammo should I be using to avoid this problem, as well as the jamming issues mentioned above? Thanks.
 
Inspect your gas cylinder assy from the muzzle to the buttplate (direction). Look for:

* loose gas plug
* front band and gas cylinder tight against the shoulders on the barrel (aligned right)
* No front band rattle (loose gas cylinder, sliding back and forth ; misaligned gas flow)
* Greased receiver with greased op rod guide (no friction anywhere)
* Greased op rod hump, greased bolt lugs and bolt raceways

Get back to us and keep us updated with your trouble shooting progress! :D
 
I've had at least a half dozen clients rifles come in with "failure to eject" issues over the past couple months with rifles that normally functioned flawlessly.

EVERY single one was caused by a stuck gas piston.
what causes a stuck gas piston you ask?

- lubricant of ANY kind contaminating the gas cylinder and varnishing to the cylinder walls and piston surface.... combine that with a couple hundred rounds worth of powder and carbon residue..... and you have a seized gas assembly which will seriously impede ejection.
- one instance was a new rifle with the gas sytem spindle valve closed.
- I have also seen rust residue from guys washing thier gas assembly parts with water :confused:

so, best advice from my bench...... NO Lube or cleaning products that leave a protective film go anywhere near your gas assembly..... period.

I use varsol or plain old gasoline for the gas assembly and allow the parts to air dry prior to reassembly.
 
Well, how not to look like a complete doofus...too late. :redface:

M14Doctor has one of my other M305's right now to bob the barrel and fix some ejection issues - no doubt it was one of those he's talking about.

Yes, my problem with the M305 I started this thread with is: a stuck gas piston. Not enough cleaning? NO - rain water got in there while I was hunting and I wiped down the bore and everything else, EXCEPT the inside of the gas cylinder. D'oh!! My only excuse is the lack of time to do things properly with a demanding wife and two young boys. :rolleyes:

So, I have cleaned off the piston and polished it (gently!), but a film of rust still exists inside the gas cylinder.

Hungry here: Rust? Shoot it lots! :D

What do you gurus recommend?? I am in your debt in advance.
 
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Sharkson said:
So, I have cleaned off the piston and polished it (gently!), but a film of rust still exists inside the gas cylinder.

Hungry here: Rust? Shoot it lots! :D
Click to expand...


Much obliged Hungry!

It's almost time to buy that press and start reloading, as my youngest troublemaker is almost 4! Just need time in large enough blocks to not make squibs or double loads (can you even put a double of powder in a 7.62x51 case?).

Up to the range on Saturday to shoot lots! :D
 
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