M14 Forum

Mikey · February 19th, 2012, 12:23 PM

To give a little background I had an m14 built a little while back and apart from the op rod the gun has been outstanding. As it was my first m14 I didn't really know what to look for in the surplus GI parts and bought what was advertised as an excellent condition op rod - turns out it was not.

This first came to my attention when m118lr ammo popped the op rod right out of its track - turned out the tab was well out of spec. Had it re-welded by Columbus machine works who did an excellent job. and dropped in a sadlak nm op rod spring guide

Unfortunately - this revealed a new problem - every few shots, the op rod catches on the diss-assembly notch and holds the bolt open on a loaded mag and has to be pushed down to chamber the next cartridge.

I'm guessing this means my op rod is slightly bent - though I couldn't really tell where - I tested it with the spring and guide removed and it still pushes up into the diss-assembly notch when I pull it back.

Anyway, I wanted to find out if I am correct in this diagnosis and if so what my options are?

Any help is greatly appreciated.

Visigoth9 · February 19th, 2012, 02:09 PM

did you drop in a fresh new shiny op rod spring to go with the spring guide?

maybe start there...

but you raise a question I have...

about how far the op rod should travel....

should it make it back to the dismount notch under normal firing?

BDH · February 19th, 2012, 02:33 PM

How does the tilt test do? Is the op rod guide on the bbl straight?

Bruce

Mikey · February 19th, 2012, 04:13 PM

It passes the tilt test other than hanging up on the notch - there is a small hangup when the tab is about halfway past the start of the notch but I have to be barely tilting the rifle for that to slow it down

- the spring only has less than 500 rounds on it and I don't currently have any other springs to try.

The op rod guide appears strait on the barrel.

Also, I don't know how far the op rod should travel - but that does make an interesting question.

jake2far · February 19th, 2012, 04:48 PM

The make of the receiver, condition of the receiver, timing of the barrel, alignment of the gas cylinder on the barrel compared to the op rod tip, pictures of the components, and a list of other parts, such as bolt.
Is the bolt roller making contact with the receiver just below the front of the sight platform?
Pictures assembled and disassembled, pics of the cam in the op rod, pics of the tab, pics of the barrel extension showing the feed ramps, compare how much wiggle the op rod has in its track.

It can be one thing or several stacked up to cause this.

If any place can help it is on this Forum.

Jim

wrongside · February 19th, 2012, 04:50 PM

I was told not to shoot the M118LR because it might be a little to hot for the op-rod. Advised not told ! Was I advised wrong?

Mikey · February 19th, 2012, 05:06 PM

Quote:

Originally Posted by jake2far

The make of the receiver, condition of the receiver, timing of the barrel, alignment of the gas cylinder on the barrel compared to the op rod tip, pictures of the components, and a list of other parts, such as bolt.
Is the bolt roller making contact with the receiver just below the front of the sight platform?
Pictures assembled and disassembled, pics of the cam in the op rod, pics of the tab, pics of the barrel extension showing the feed ramps, compare how much wiggle the op rod has in its track.

It can be one thing or several stacked up to cause this.

If any place can help it is on this Forum.

Jim

Okay, gonna try not to miss anything here.

-The receiver is SEI - purchased new for the build
-The barrel is correctly timed as far as I can tell
-The op rod tip is centered on the gas cylinder
-The bolt is an old Springfield USGI
-op rod is Winchester USGI as is trigger group
-I have both a sadlak nm and USGI op rod guides - when replicating the issue at home it seemed less pronounced with the GI op rod guide - will need to confirm this at the range.
-there is a little wiggle in the op rod - the top moves back and forth a bit
-the bolt roller does not appear to contact the receiver

I'll work on getting some pics

EBRbuilder · February 19th, 2012, 05:31 PM

Quote:

Originally Posted by wrongside

I was told not to shoot the M118LR because it might be a little to hot for the op-rod. Advised not told ! Was I advised wrong?

This is totally wrong as the only ammo we used to test M14EBR-RIs is M118LR. I have personally shot 20K rounds of M118LR through M14s and can assure you that there is no problem whatsoever with its use. It is the prefered ammo used in AFG bythe Army.

SOCOM42 · February 19th, 2012, 05:48 PM

With no spring, rod guide or bolt, run the rod all the way to the rear.

Look to see if the gap between the rod and the shelf is constant along the whole shelf lenth.

This is an indicator of straightness.

It should be parallel to the shelf and ideally resting on the shelf.

Mikey · February 19th, 2012, 05:50 PM

Okay, took some pics - hopefully everything's here!

Barrel timing

Bolt closed w/op rod

Take down notch

op rod wiggle - held against receiver

op rod wiggle - pulled away from receiver

Op rod tab - un-parked from re-weld - not wear

Receiver minus op rod

Bolt roller

Bolt forward

Op rod in forward position

Op rod in intermediate position

op rod in rearward position / diss-assembly notch

Gas cylinder / op rod alignment

SOCOM42 · February 19th, 2012, 05:52 PM

Rod is bent, you can see in pics

Mikey · February 19th, 2012, 05:53 PM

Quote:

Originally Posted by SOCOM42

With no spring, rod guide or bolt, run the rod all the way to the rear.

Look to see if the gap between the rod and the shelf is constant along the whole shelf lenth.

This is an indicator of straightness.

It should be parallel to the shelf and ideally resting on the shelf.

- it angles upward towards the back end - you can see in the pics i just posted - tried it w/out the bolt and same result.

-my bad - i was writing this response when you posted - didn't see it till after

SOCOM42 · February 19th, 2012, 05:55 PM

Quote:

Originally Posted by Mikey

- it angles upward towards the back end - you can see in the pics i just posted - tried it w/out the bolt and same result.

Just posted, rod is bent

Mikey · February 19th, 2012, 05:57 PM

Quote:

Originally Posted by SOCOM42

Rod is bent, you can see in pics

Yeah that's what I figured - as this already needed re-welding am I better off just getting a new SEI forged op rod and if so, should I get one and see if it drops in first or do I just need to send the gun in and have andy fix it?

SOCOM42 · February 19th, 2012, 06:02 PM

Quote:

Originally Posted by Mikey

Yeah that's what I figured - as this already needed re-welding am I better off just getting a new SEI forged op rod and if so, should I get one and see if it drops in first or do I just need to send the gun in and have andy fix it?

That one can be straightened out. Any new rod correctly made should drop right in and pass the visual test I described. The rest is your decision.