M305 Op Rod Bent?

The tab on new oprods are generally over sized. This is because they have to fit in "worn receivers" and/or production tolerances.

Ill see if I can find the instructions I used. some people stone them, I went with 400 emery cloth.

Basically all you do is use a marker to darken the oprod and tab. Stick it in, try to move it, take it out, few passes on the points that show the marker removed. re-apply marker repeat. It also helped to take a bent stick (or substitute) and the emery cloth to schmoooge out all the milling marks in the op rod tab slot.
 
How tight is the op rod in the guide? If the guide is pointing the op rod off centre of the piston, and it is tightly guided by the guide, you can hardly blame the op rod. If it's loose within the guide, then there is potential for it to be misdirected by the interaction with the receiver, but if its got little play, its nothing but a cylinder being pointed in the wrong direction (or in the right direction, and the gas system is off centre). I'm just thinking I wouldn't be in such a rush to buy a new oprod and assume that will cure the problem. You need another op rod to test it with, or a precision made rod to slide into the guide and see how it lines up.
 
If you unhook the op rod from the receiver channel, does it still point off centre of the gas piston? That would tell you if the oprod is bent, or if its something else.
 
Grizzlypeg is right, a good indicator

When I've fit the couple dozen or more RWB oprods from dlask, the first step has been to break the sharp corners of the bottom of tab, just a weeeee bit , IF the tab won't start to engage.
The next step is to file with a triangular needlefile , the vertical bearing surface above the tab.
This bearing point and how you treat it is going to determine everything when it comes a silky hydraulic like oprod fit.

File that tab until the oprod fully engages the receiver.
Then use machinist blue or felt pen to darken All shiny areas.
Reinstal oprod and force it a bit so you get witness marks in the coloring, showing bind points.

Very little should need to be filed or stoned other than what I've indicated above.
Once tab to receiver fit is established, begin using fine lapping compound... With the spring and guide rod installed as an assist to lapping instead of the ol rubber mallett ;)

There's a right way to do it.... And many many wrong ways ;)
 
Well, figured out a couple things. The grinding I was feeling was the top of the spring rubbing as it was compressing. I greased it nice and good. Still rubs but alot smoother.

And the part that was binding was the top rear of the bolt.


bolt by http://www.flickr.com/people/hachey_photography/,

So I polished a few spots with some sand paper. Lubed it up and I'm just going to shoot it like it is. I think I was over reacting a little.
 
Take your spring guide out and file the end on the surface that butts against the receiver when you install it. So the guide rod goes deeper into the receiver slot. Keep going untill spring no longer binds between tube and rod. A common alteration to perform on aftermarket guide rods.

Re reading my post, I'm not explaining that very well hehehe.
If you look at the connector pin end of the rod that is a wedge with an oblong hole in it, the "flat" site of the wedge that rests up inside the receiver slot when you put the pin in. Or the side of the wedge that is up between pin and receiver... Get what I mean hehehe
Filing that side, corrects the angle the guide rod protrudes into the oprod tube and you know it is centered when the spring no longer rubs ;)
 
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Checked my Op Rod last night. Although the contact point between the piston and the Op rod are off center, the cause seems to be the gas cylinder that seems misaligned. The gas port of the barrel lines up perfectly with the port of the gas cylinder but the piston is off center on the piston by 3 mm or so.

I'm not concerned from a safety perspective (should I be...) but more from an accuracy perspective. Any thoughts on a fix short of replacing the gas system?
 
Pr589 said:
Checked my Op Rod last night. Although the contact point between the piston and the Op rod are off center, the cause seems to be the gas cylinder that seems misaligned. The gas port of the barrel lines up perfectly with the port of the gas cylinder but the piston is off center on the piston by 3 mm or so.

I'm not concerned from a safety perspective (should I be...) but more from an accuracy perspective. Any thoughts on a fix short of replacing the gas system?
Click to expand...
Over time an dramatically off center op-rod can cause un needed pressure on the bolt roller witch could cause it to snap off and also other extreme wear on other working parts witch can lead to failure quicker than normal.
In summary, a properly timed and tuned rifle not only provides for great accuracy but also over time less mechanical failures and less cycling issues.
Now if your spline ways are cut off spec or your rifle is not aligned I would see what the aftermarket manufacture has to say about to correct these issues or if not try to find replacement parts to rectify this issue.
 
Maybe a dumb question but have you checked your barrel indexing?
Cause an out of index barrel causes these problems as well
 
Over indexing was the first assumption but using bars across the front sight-base and the receiver show no obvious indexing issues. In an earlier post, ACP had indicated that the vertical positioning of the barrel gas port was the only real way to measure indexing - but special tools are apparently needed.

I had decided to live with it (assuming it was a spline way issue) until I shot out the barrel and could replace it. This thread had me wondering again. Maybe a USGI or SA gas system is in my future.
 
M305 Op Rod Bent?---Update post 38

It was the Op Rod! M14kid sold me two of his norc ones he wasn't using, just got them today.

With either of the ones he sent me installed, the rod and gas piston line up perfectly and the spring doesn't even bind at all anymore. The action feels unrealistically smooth for such a beast of a rifle. Feels like a hot knife through butter now.

Thanks m14kid!
 
WTH is happening with the Norincos lately? I stupidly sold my 2005-ish full-length because I wanted a shorty, but the quality control is clearly not the same.

I was under the impression that quality had steadily improved over the years - maybe just on the M4's?

My older one was trouble-free, this new one looks like yours in terms of op-rod alignment...not good for my OCD at all..
 
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