Short M14 - Bolt Closure issue.

NavyCuda

NavyCuda

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I'm having an issue with my brand new, never fired Shorty M14. Basically the bolt doesn't always want to close. Before cleaning and greasing the bolt would not close every time when the bolt was allowed to be carried forward by the spring.

After greasing and trying to cycle the action more the bolt would close when chambering snap caps. Chamber checking, the bolt would not close and would have to be pulled further back to get the bolt to close. You could also feel, even while chambering the snap cap the the bolt would momentarily pause before going into battery.

I believe that I have identified the point of contact that is the problem and I'm looking for thoughts and ideas on how to fix it. More on that at the end of this post.

[youtube]eK3L_MR-knI[/youtube]

m14bolt.jpg


You can see where the bolt is contacting just behind the lug on the bolt and along the structure for the lug on the receiver.

What can I do to fix this, would taking a small fine file to the receiver side and smoothing the edge be ok? Is there any risk damaging important hard surfacing? Any other solutions that are eluding me?
 
there's no issue here. It isnt designed to be babied. To chamber, always fully pull the op-rod back and let go freely all the way.
 
chemo said:
there's no issue here. It isnt a design to be babied. To chamber always full pull the op-rod and fully let go.
Click to expand...

This is my second m14 and the other one does not hang up at all and can be closed without issue. Also I can feel the bolt binding when allowed to close under spring power, this does not feel smooth or correct.
 
Making a youtube was a good idea.

I don't think this is going to be a problem. If the bolt closes on a live round when you let the op rod spring do it's job from full compression it will be fine. I bet within 40 rounds of live ammo this will loosen up. If you want, visually confirm the bolt has gone all the way into battery before each round until you run the first 30 or so rounds through it. A better op rod spring guide can't hurt.

chemo said it; let the bolt fly from full open. That's what happens when it does its semi auto thing.

Personally I wouldn't take any metal off.
 
2 places to check.
The area you mention and ... Check the bottom edge of the left bolt lug recess. I have found burring on the left side on a few receivers. Debur and good to go.

Now, on the right side, the ledge the right lug rides on can be stoned as this area can have roughness I would attribute to tool chatter during machining.
Polish this ledge and break the corner just slightly at the forward end where the bolt lug recess starts. Don't over do it.
 
M14Doctor said:
2 places to check.
The area you mention and ... Check the bottom edge of the left bolt lug recess. I have found burring on the left side on a few receivers. Debur and good to go.

Now, on the right side, the ledge the right lug rides on can be stoned as this area can have roughness I would attribute to tool chatter during machining.
Polish this ledge and break the corner just slightly at the forward end where the bolt lug recess starts. Don't over do it.
Click to expand...

Is a jewelers file acceptable to deburr this edge? Is there any risk of damaging anything, such as hard surfacing while smoothing the edge?
 
Jewelers files are acceptable. The ledge itself shouldn't need too much work to smooth it to a point where she doesn't bind. Breaking the corner of the bolt lug recess needs very careful attention. It's only the top edge of this corner that you want to break. Feel it with your thumnail, if it's smoth at the corner, leave it be. Deburing should not require much work and it should not affect hardness.
Just work slow, check fitment frequently. Cleaning and greasing each time.
 
Great idea using a video. That certainly helps things significantly. I would just rack that baby a few times while watching "Full Metal Jacket". You did the right thing by greasing the heck out of things.

Then after all that 'deburring' while racking and listening to R Lee Ermey say, "Private Pyle, did you join my Marine Corps to suck ####?" Have another examination to see the engaging surfaces are working like M14Doctor sez! He's got (way lots) more experience than me! ;)

Cheers,
Barney
 
Hungry said:
Great idea using a video. That certainly helps things significantly. I would just rack that baby a few times while watching "Full Metal Jacket". You did the right thing by greasing the heck out of things.

Then after all that 'deburring' while racking and listening to R Lee Ermey say, "Private Pyle, did you join my Marine Corps to suck ####?" Have another examination to see the engaging surfaces are working like M14Doctor sez! He's got (way lots) more experience than me! ;)

Cheers,
Barney
Click to expand...

That's a great movie, I might just have to watch it again!

I've noticed as I cycle the snap caps more the issue gets less and less, but I thought I'd document it and get some advise to be sure. I am addicted to Mobil 1 XHP 462... I put it on just about everything. I even gave a sample to Charles Martel but haven't heard back if he's tried it yet.

Thanks M14doctor and Hungry for your replies!
 
michaelsabre said:
Short Cycling it is.

The rifle is good. If you want to improve it, just shoot 200 rds or cycle your rifle 200 times.
Click to expand...

Short cycling is an all together different problem, as this rifle has not been fired I doubt short cycling is my issue. My problem is a simple mechanical bind point during rotation of the bolt.

I'm going to try Hungrys suggestion of cycling the action while watching Full Metal Jacket. "This is my rifle, this is my gun! This is for fighting, this is for fun!"
 
NavyCuda said:
Short cycling is an all together different problem, as this rifle has not been fired I doubt short cycling is my issue. My problem is a simple mechanical bind point during rotation of the bolt.

I'm going to try Hungrys suggestion of cycling the action while watching Full Metal Jacket. "This is my rifle, this is my gun! This is for fighting, this is for fun!"
Click to expand...

:)

How it shoots? Any jam in shooting?
 
Kayser Sose said:
..jeez, I'd rather go shooting than 'work my action' watching a movie.... lol
Click to expand...

Well it isn't convenient for me to just at the spur of the moment head out to the range. Besides, I prefer to hand cycle the action of all my firearms a number of times before the first time I fire it.
 
I've been thinkin about this some more and I want you to check a couple things.
Clean out the grease in the oprod's roller pocket and check for any wear marks in and around where the roller makes contact at the rear of the pocket.
- also when riding the oprod and slowly closing the bolt, does the top of the bolt face hang up on the upper face of the barrel?
 
M14Doctor said:
I've been thinkin about this some more and I want you to check a couple things.
Clean out the grease in the oprod's roller pocket and check for any wear marks in and around where the roller makes contact at the rear of the pocket.
- also when riding the oprod and slowly closing the bolt, does the top of the bolt face hang up on the upper face of the barrel?
Click to expand...

Even through the grease I can see some contact marks on the op rod, in the roller guide. Nothing substantial but a barely visible mark. Op rod is slated for replacement.

There are contact marks on the bolt face and the barrel that are mostly on the top side, but only on the face, not on the outside diameter.

I believe that the only contact point is the location I indicated, I inspected the other side very closely and it looks like it is possible that it might occasionally contact but I saw a crack of light which suggests no contact.

After watching full metal jacket, I put about another 100 cycles on the action without a snap cap and riding the op rod to be able to feel what was going on. The bolt still binds up when I unlock it from battery and pull it back a few millimeters, any more than 2 cm back and it always closes now. During reloading drills I rarely feel the bolt hanging up when releasing from the bolt stop and letting the spring drive the bolt into battery. Previously it felt like there was two distinct stages in the bolt travel, now it's mostly just one stage.
 
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