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Feed Issues, Rock-ola James River Armory

This is a discussion on Feed Issues, Rock-ola James River Armory within the Modern M14 forums, part of the M14 M1A Forum category; I live about 15 mins south of you. I have a couple of spare pistons you're welcome to try....


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Old May 19th, 2017, 09:27 AM   #46
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I live about 15 mins south of you. I have a couple of spare pistons you're welcome to try.

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Old May 19th, 2017, 11:01 AM   #47
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I just took the pistons out of my LRB and JRA rifles and found that despite never having cleaned them or had issues that may be caused by dirty pistons; they weren't that dirty, very little carbon buildup in either one and I cant imagine the amount of crud it would take to cause feed issues. I do always clean out the cylinder and clean the pistons, which are standard types in my 4 M14 rifles.

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Old May 19th, 2017, 11:53 AM   #48
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Quote:
Originally Posted by masspatriot View Post
Fired 60 rounds, three different types of ammo and four magazines. New extractor, ejector and spring, thourough cleaning of entire gas system. Can't cycle 4 rounds in a row.
I called Jame River Armory, very friendly. We went over a lot of items. Diagnosed as either gas piston or gas cylinder. They suggested Sadlak NM with coating. On order. Will update after installing and test firing. It is very accurate, I must say.
Hi Mass Patriot,
Don't waste your time or money getting another piston, that is not it, providing you did get the right small drill bit and clean the tail of all carbon fouling too. It is not your gas cylinder either, unless the rear ring that holds the spindle valve port tight to the barrel is leaking massive amounts of gas and is shaky loose. Which reminds me, make sure your spindle valve screwdriver slot is straight up and down, vertical, when holding the rifle horizontal, not partially sideways or horizontal. In other words, perpendicular to the barrel. 90 degrees, not 75 or 80

That would be easy to spot, either condition above. One because there would be black marks from the gas leaking around the ring, and etching, and the other because it would be rattling loose.

In all the years of inspecting hundreds and hundreds of gas cylinders with ball micrometers and snap gauges, I've only seen one that was worn out from firing....and have never seen a g.i. piston worn out....and I've seen some rough ones.

If you didn't mount a scope and put too long of a machine bolt in and it is not dragging on the left bolt locking lug and robbing gas, and the left helix side wall cuts aren't interfering with bolt travel, there are only two things that can cause this issue.

One, I already covered before is the chamber reaming job being too rough and hanging brass until enough gas is robbed to not allow a complete cycle.
Two, is the receiver bridge cut for firing pin retraction.

You can visibly check the first by looking at the chamber with a good bent neck light with the trigger group and bolt out of the way.

You can check the second by removing the trigger group and taking the action out of the stock and standing it on the flash suppressor, barrel down and heel straight up like a tomato stake. Leave everything else in the action.

With bolt closed in battery, reach under the receiver heel and push the firing pin forward, as if your finger were the hammer hitting it, then hold the heel with that hand and with your other hand, take one finger and pull gently on the op rod handle and watch the firing pin and see if it rotates and will allow the bolt to open. If it takes a lot of force or more than one finger, the cut is wrong or insufficient to allow retraction under normal and violent retraction.

The tail of your firing pin and the bridge will tell the tale and show gouges or bad wear characteristics on it. Read, shiny spots, cuts, scrapes, etc.etc....You can polish them up and it may help. If the cut is wrong, very common by the way, it can be fixed easily.

If it's a rough chamber or too tight a headspace, or combination of both, it will need to be fixed by a professional. Post pics of the receiver bridge from the rear and underneath it, looking forward with the bolt and trigger group out of the way. If it is the problem, I can identify it. So can username Ironworker here. He has an excellent thread in the Gunsmithing sub-forum here that you can compare yours to.

Let me know what you find........rip

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Old May 19th, 2017, 03:45 PM   #49
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Wow, I'll check both of those items tomorrow. When I was working on the bolt, I did notice a rough edge on the firing pin and think it might be hitting something. I was trying to find a picture of how the receiver should look in that area and what the FP might be contacting.
Thanks everyone, and the offer to test a new piston.

Phil

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Old May 20th, 2017, 05:52 AM   #50
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Quote:
Originally Posted by ripsaw View Post
Hi Mass Patriot,
Don't waste your time or money getting another piston, that is not it, providing you did get the right small drill bit and clean the tail of all carbon fouling too. It is not your gas cylinder either, unless the rear ring that holds the spindle valve port tight to the barrel is leaking massive amounts of gas and is shaky loose. Which reminds me, make sure your spindle valve screwdriver slot is straight up and down, vertical, when holding the rifle horizontal, not partially sideways or horizontal. In other words, perpendicular to the barrel. 90 degrees, not 75 or 80

That would be easy to spot, either condition above. One because there would be black marks from the gas leaking around the ring, and etching, and the other because it would be rattling loose.

In all the years of inspecting hundreds and hundreds of gas cylinders with ball micrometers and snap gauges, I've only seen one that was worn out from firing....and have never seen a g.i. piston worn out....and I've seen some rough ones.

If you didn't mount a scope and put too long of a machine bolt in and it is not dragging on the left bolt locking lug and robbing gas, and the left helix side wall cuts aren't interfering with bolt travel, there are only two things that can cause this issue.

One, I already covered before is the chamber reaming job being too rough and hanging brass until enough gas is robbed to not allow a complete cycle.
Two, is the receiver bridge cut for firing pin retraction.

You can visibly check the first by looking at the chamber with a good bent neck light with the trigger group and bolt out of the way.

You can check the second by removing the trigger group and taking the action out of the stock and standing it on the flash suppressor, barrel down and heel straight up like a tomato stake. Leave everything else in the action.

With bolt closed in battery, reach under the receiver heel and push the firing pin forward, as if your finger were the hammer hitting it, then hold the heel with that hand and with your other hand, take one finger and pull gently on the op rod handle and watch the firing pin and see if it rotates and will allow the bolt to open. If it takes a lot of force or more than one finger, the cut is wrong or insufficient to allow retraction under normal and violent retraction.

The tail of your firing pin and the bridge will tell the tale and show gouges or bad wear characteristics on it. Read, shiny spots, cuts, scrapes, etc.etc....You can polish them up and it may help. If the cut is wrong, very common by the way, it can be fixed easily.

If it's a rough chamber or too tight a headspace, or combination of both, it will need to be fixed by a professional. Post pics of the receiver bridge from the rear and underneath it, looking forward with the bolt and trigger group out of the way. If it is the problem, I can identify it. So can username Ironworker here. He has an excellent thread in the Gunsmithing sub-forum here that you can compare yours to.

Let me know what you find........rip
Is the op rod spring installed during the test you described above?

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Old May 21st, 2017, 04:59 AM   #51
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Quote:
Originally Posted by masspatriot View Post
Is the op rod spring installed during the test you described above?
Yes...here is the thread to how it should look on the bridge cut on the right side from shooters position.

Firing pin retraction surface

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Old May 21st, 2017, 07:37 AM   #52
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I believe the FP and safety bridge is the issue

Ripsaw, I believe nailed it. I have captured a video showing that if I keep slight pressure on the firing pin will pulling the op rod back, there is a catch, then enough pressure gets the bolt to jump and retract. Is there a way to upload a short video?
Attached Images
File Type: jpg IMG_1942.JPG (547.5 KB, 21 views)


Last edited by masspatriot; May 21st, 2017 at 04:52 PM.
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Old May 21st, 2017, 07:40 AM   #53
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I don't know but I would like to see it.

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Old May 21st, 2017, 07:56 AM   #54
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I love these threads that make me get my rifle and a magnifying glass out to look at things I've never noticed before.

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Old May 21st, 2017, 09:58 AM   #55
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More pictures after tear down

I removed scope and mount (screw was not protruding). Removed clip loading block. cleaned grease. Took pics.
One thing I noticed: The firing pin does not retract without force from the bot. It resists at the last 32nd of an inch. Should it move freely back and forth, maybe by shaking the bolt? Also the firing pin is showing signs of battering. The safety bridge looks close to other's pictures, no visible wear marks.
Attached Images
File Type: jpg IMG_1954.JPG (294.5 KB, 16 views)
File Type: jpg IMG_1951.JPG (61.0 KB, 15 views)
File Type: jpg IMG_1952.JPG (62.5 KB, 15 views)
File Type: jpg IMG_1948.JPG (96.7 KB, 16 views)
File Type: jpg IMG_1949.JPG (61.8 KB, 16 views)

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Old May 21st, 2017, 11:24 AM   #56
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Quote:
Originally Posted by masspatriot View Post
Fired 60 rounds, three different types of ammo and four magazines. New extractor, ejector and spring, thourough cleaning of entire gas system. Can't cycle 4 rounds in a row.
I called Jame River Armory, very friendly. We went over a lot of items. Diagnosed as either gas piston or gas cylinder. They suggested Sadlak NM with coating. On order. Will update after installing and test firing. It is very accurate, I must say.
Why not a GI piston?

Sadlak is an unnecessary upsale.

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Old May 21st, 2017, 01:21 PM   #57
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Quote:
Originally Posted by Roadkingtrax View Post
Why not a GI piston?

Sadlak is an unnecessary upsale.
The guy at James River Armory suggested it.

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Old May 21st, 2017, 02:48 PM   #58
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Quote:
Originally Posted by masspatriot View Post
The guy at James River Armory suggested it.
If your rifle isn't cycling with a GI piston, and there's nothing wrong with that GI piston, then I doubt a Sadlak will fix it regardless of how much an upgrade someone thinks they are.

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Old May 21st, 2017, 03:30 PM   #59
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Video Download site

This is available for 30 days

https://www.icloud.com/attachment/?u...OV&sz=54849526

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Old May 21st, 2017, 04:53 PM   #60
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Quote:
Originally Posted by ripsaw View Post
Yes...here is the thread to how it should look on the bridge cut on the right side from shooters position.

Firing pin retraction surface
I found that the firing pin hangs in the bolt, which might be causing the resistance of the bolt to retract. Thoughts?

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