Another shorty M14, short stroking...

Xman

Xman

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My situation is a bit different. Before I got it shortened my M14 worked flawlessly with any ammo I fed it. Now, it short strokes but not right away; the first 3-4 rounds after I clean it feed just fine but after that, it will eject but it won't grab a new round.

Other than a barrel shortening and gas system unitizing nothing is different. I checked the gas pathway; the holes are lined fine all the way, I cleaned the hell out of every part including the gas plug and the ammo is clean, non-corrosive, the piston slides just fine with no looseness... Like I said, nothing is different other than barrel length and unitizing. Why does it quit working after the first 3-4 rounds?
 
Make sure nothing is binding and give it a damn good oiling. (not the piston.) I don't know if it makes a differance or not but mine had excessive bolt slop. I started neck sizing and the short stroking stopped. Then I got a TRW bolt from Hungry and life is good.
 
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Because the piston only is acted on by gas pressure once the bullet is past the opening in the barrel, so a shortened barrel=less time and therefore less pressure. I'd guess 4-5 rds is the time it takes to heat the metal parts just enough that they impeded movement just enough to cause you problems.

I bet it gets worse if you fire fast, and the longer you do it the worse it gets.
 
Xman said:
But nothing is different compared to before chopping . Why would it star acting up now ? It worked flawless before.
Click to expand...

The gas tap from the barrel is effectively closer to the muzzle now. Less duration of gas pressure. That said, shorty's do work right?
 
Wally, I understand the the SOCOM shorties have the exact same size gas bleed hole in the barrel. Maybe other part are different, like a softer spring?
 
M14 Fun

Okay.... hmmmm...

Ammo: Factory or handloads?

Handloaded? What powder are you using? Ball powder was designed FOR the M14's .308 cartridge hence a faster burning rate and cycle rate that the venerable M1 Garand.

Action/bolt: Greased lugs, greased op rod raceways, greased hammer nose/face?

Unitized gas cylinder: Without looking or close examination it's hard to tell. I'm hoping that there is no bleeding out of the gas anywhere along the gas cylinder body when / after the welding was carried out. Spare gas cylinders/ assemblies are not expensive.

Thoughts? Get back to us when you can!

:cheers:

Barney
 
Hungry, the ammo I've been using is Israeli ball and Federal soft point, 150gr. I've used the same ammo before the chop with great results. Even took my deer last season with the un-chopped gun and the Federal soft point. Never a failure of any sort. And yes to all the grease question. I read one of your older posts yesterday and greased up all those parts after. No joy!

The gas plug I'm using is a well worn one that I just got on EE (my original went missing). It has a few corrosion pits on the head, on the flat surface that goes in the tube, ahead of the threads.

I borrowed a new one from a friend and I will give it a try today just to make sure that the gas plug is not where I'm losing gas. If that doesn't fix it (and I honestly don't expect it will) I might just go for a whole G.I. gas system, cylinder and a plug. Would that fit on the Norinco barrel no problem?
 
Xman said:
Hungry, the ammo I've been using is Israeli ball and Federal soft point, 150gr. I've used the same ammo before the chop with great results. Even took my deer last season with the un-chopped gun and the Federal soft point. Never a failure of any sort. And yes to all the grease question. I read one of your older posts yesterday and greased up all those parts after. No joy!

The gas plug I'm using is a well worn one that I just got on EE (my original went missing). It has a few corrosion pits on the head, on the flat surface that goes in the tube, ahead of the threads.

I borrowed a new one from a friend and I will give it a try today just to make sure that the gas plug is not where I'm losing gas. If that doesn't fix it (and I honestly don't expect it will) I might just go for a whole G.I. gas system, cylinder and a plug. Would that fit on the Norinco barrel no problem?
Click to expand...
When was the last time you cleanned & removed the carbon build up in the gas plug???
 
Satain said:
When was the last time you cleanned & removed the carbon build up in the gas plug???
Click to expand...

Two days ago...I got it spotless.

I tried a new gas plug today and still the same problem but I think I figured it out. I think the bolt binds on the hammer on it's way backwards. I finally wised up to pull the trigger and release the hammer before I manually work the handle again and I was able to feel it every time. I took it apart and I can see a small indent where the rear edge of the bolt has been slamming into the body of the hammer. The bolt gets hung up in that dent pretty good. I imagine that it is enough to cause short stroking with a shorty barrel.

I am getting ready to do a sanding and smoothing job on the hammer and will report back.
 
What kind of stock is it in?
If the hammer/bolt interface is too close, this can be corrected by bedding trigger/receiver. In doing so, adding a few thou to the bedding surfaces all around.
Too much and trigger can fail safety check, too little and bolt can bind on hammer.
Shortening shouldn't have had any effect.
I unitized this gas system and facilitated the shortening. Pretty routine and everything passed inspection. Too bad you didn't send the entire rig, I might have caught this issue in test fire.
If you have a caliper, measure from the top rear stock/receiver bearing surface(horseshoe) to the top of the trigger pads at rear of trigger inlet.
I'll need a measurement in thou to compare with.
 
M14Doctor said:
What kind of stock is it in?
If the hammer/bolt interface is too close, this can be corrected by bedding trigger/receiver. In doing so, adding a few thou to the bedding surfaces all around.
Too much and trigger can fail safety check, too little and bolt can bind on hammer.
Shortening shouldn't have had any effect.
I unitized this gas system and facilitated the shortening. Pretty routine and everything passed inspection. Too bad you didn't send the entire rig, I might have caught this issue in test fire.
If you have a caliper, measure from the top rear stock/receiver bearing surface(horseshoe) to the top of the trigger pads at rear of trigger inlet.
I'll need a measurement in thou to compare with.
Click to expand...

It's in the VLTOR you see in my avatar and I will go buy a caliper tonight and measure it. But I can tell you right now that I sanded down a few thousands when I first put the rifle into this stock, so that's probably the issue right there. I didn't know how snug the trigger group was supposed to fit in so I sanded it till it popped in fairly easy. I imagine the trigger guard shouldn't close too easily?

What's the proper outside dimension that I should have from the top of the stock (where the receiver sits on it) to the the top of the metal housing that the trigger sits in? From top outside to the bottom outside, on the outside of the stock, I guess. And what kind of shims could I use? Thanks!



Edit:

Thomas, I got a caliper and I measured what you asked: one inch+ eight tenths of an inch + ten one thousands.

I am not sure how to read that. 18/100ths and 10/1000ths?
 
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OK, I officially give up! :mad:

I shimmed between the stock and the receiver to where the action was sliding backward smooth like butter when pulled by hand, I sanded and smoothed bolt, inside receiver where bolts slides along, the hammer face that interacts with the bold....still no joy.

I've greased and oiled everything that should be greased and oiled, cleaned the insides of the gas system (tube, piston and plug)...

I got frustrated and I started cutting off coils of the spring...nothing. I stopped after I cut about 11 or 12 coils. Still comes about an inch short of stroking through a full cycle...

I'm ready to throw it in the garbage...I've gone through about 200 dollars worth of ammo in the last three days, just trying to fix this gun...
 
Have you tried that technique of looking for binding by removing the oprod spring, and tilting the rifle muzzle down and up to see if the weight of the oprod and bolt are enough to have it smoothly travel back and forth by gravity, without any binding? Hammer needs to be cocked to avoid that interferance.

I feel for you on the ammo wasting. I've been through that heartache on another rifle.
 
I don't want to sound like a ####, but with everything else apparently having been tested, the only two things I can think of is that you either haven't indexed your gas piston correctly or the gas port is obstructed somehow? I know they're both longshots, but I'll be damned if I can figure it out without the rifle in front of me otherwise...

Can you run a drill bit or a pin punch through the gas port into the barrel? Does the gas piston slide back - with its keyed shaft fully rearward - when you simply tilt the rifle backwards (minus oprod and spring, of course)?

What a conundrum...

-M
 
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