Roller Failed Again - Op Rod Issue?

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sobo4303

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Well...I fired about 30 rounds through the beast and the roller failed again.

Ammo was Remy 150 gr Core-Loct and Win 150 gr. The rifle was nicely sighted in for 300 yards and I was shooting gongs.

I am wondering, from the "shiny" areas in the Op Rod whether there is an issue there. The Op Rod is the Norky, the one that came with the rifle.

There is absolutely no signs of pressure issues on the cases. Could it be though, with the tighter headspace, that there is too much for the op rod/roller? The reason I ask is that on the op rod, there appears to be some metal wear on the op rod where the bolt rotates out of battery after firing (near the center of pic #3 - you can kind of make out the ridge I see). It looks like some "smoothening" hard to see in the pics though. To me, it seems that the op rod, while fine for the norky parts, is not in spec for usgi stuff because the metal on the right side of the operating "track" appears to have a "hump", which I note is now peaning as if the roller wants a smoother track.

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Ideas/thoughts are most welcome.
 
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what do you mean "failing again"?

I've had m14doctor repair my bolt roller, though on mine only the spring clip wentmissing/broke...
 
I thought that it was a metal edge some sort was causing this to happen. Just never thought that it would be in the op-rod in the bolt roller channel.
Satain said:
1 more question for ya sobo4303.
Does were the roller seperated matches the grove on the reciver on witch it rolls on?
The grove is shown here;
m14rcvr.jpg

Just wondering if it they made the roller wall to thin on yours as mine never has shown this issue yet.
Click to expand...
Yep you need a new op-rod and fix the broken part and you will be good to go.
 
I have my old norc op rod ill pull it out tomorrow after work and see if i have the same wear ..

All i know is when i dropped in my USGI op rod things got much tighter and seem to "jive" better .
 
is this a 7.62 firearms roller on the second failure?
and is the pic of the shattered roller from the second failing or first?

in every instance that i have had to replace a roller for myself or clients, it has been a roller seperation due to clip failure.
I have not personally inspected a roller that has blown apart like in the pics.

the oprod roller pocket in your pic, "appears" to be normal
the roller bearing edge on your receiver does look very rough.
Is your oprod very loose in it's track?

replacing a roller and clip is a bugger of a task and normally requires a special tool.
even with that tool it's a crappy thing to have to deal with ;)

if this is happening twice with a 7.62 roller, I would immediately suspect the roller and get one from brownells, the clip too.

I would install the new roller and ensure that with the bolt fully locked closed, there is no contact between the roller and the receiver under the roller.

I would also try a different oprod but only if you have one handy that fits
I would maybe stone that roller bearing edge on your receiver.... but only if you feel it's part of the problem.

having not seen this issue arise on this site before..... the shatttered roller thing..... I'm gonna still lean to a faulty roller..... or there is something amiss with your rifle altogether.

One last thing. This next comment is NOT a complaint or personal bash against 7.62 firearms. I have read on U.S. sites of some folks having issues with some of the newly manufactured parts coming from this company. At the same time, they are highly praised and respected in the market place. One of the issues i have seen pop up was with the new bolts, not with the rollers specifically, but some fitment issues have been reported. I would simply email the fellows at 7.62 with the pics attached and ask them if this problem has occured with anyone else's bolt/roller. It may be something they have seen and will want to correct. This is the feeling i get with reading the comments on the US sites, they are eager to put customer feedback into producing a better product.
 
Was following this thread and the related one with some concern since I had a bolt inbound from 762firearms. It arrived a couple days ago and fit my rifle perfectly with no lapping. Barrel is a Criterion chrome lined shorty. Took it to the range yesterday and fired 30 rounds of handloads, zeroing the irons, an Aimpoint M4, and a Burris pistol scope. No problems whatsoever, and my brass measures 1.630-1.631 with my Stoney Point headspace gauge. No marks on the bolt roller upon inspection. So, based on this limited testing, I'd say I'm happy with the bolt. Also purchased a gas assembly from 762firearms and it fit very well. Both bolt and gas assembly arrived about 3 weeks after placing the order. Build is now complete and load development begins.
 
M14Doctor said:
is this a 7.62 firearms roller on the second failure?
and is the pic of the shattered roller from the second failing or first?

in every instance that i have had to replace a roller for myself or clients, it has been a roller seperation due to clip failure.
I have not personally inspected a roller that has blown apart like in the pics.

the oprod roller pocket in your pic, "appears" to be normal
the roller bearing edge on your receiver does look very rough.
Is your oprod very loose in it's track?

replacing a roller and clip is a bugger of a task and normally requires a special tool.
even with that tool it's a crappy thing to have to deal with ;)

if this is happening twice with a 7.62 roller, I would immediately suspect the roller and get one from brownells, the clip too.

I would install the new roller and ensure that with the bolt fully locked closed, there is no contact between the roller and the receiver under the roller.

I would also try a different oprod but only if you have one handy that fits
I would maybe stone that roller bearing edge on your receiver.... but only if you feel it's part of the problem.

having not seen this issue arise on this site before..... the shatttered roller thing..... I'm gonna still lean to a faulty roller..... or there is something amiss with your rifle altogether.

One last thing. This next comment is NOT a complaint or personal bash against 7.62 firearms. I have read on U.S. sites of some folks having issues with some of the newly manufactured parts coming from this company. At the same time, they are highly praised and respected in the market place. One of the issues i have seen pop up was with the new bolts, not with the rollers specifically, but some fitment issues have been reported. I would simply email the fellows at 7.62 with the pics attached and ask them if this problem has occured with anyone else's bolt/roller. It may be something they have seen and will want to correct. This is the feeling i get with reading the comments on the US sites, they are eager to put customer feedback into producing a better product.
Click to expand...

Howdy Doc, here are the answers to your questions.

1) The new roller was a Brownells. Actually, I found installing the roller assembly quite easy and painless. The trick was to uniformly seat the clip and lots of grease.

2) There is a gap of about .030" between the receiver and roller when the bolt is closed.

3) The roller never makes contact with the receiver, only the op rod, at all stages of the action. That is why I suspect the op rod, as there is evidence of peening (on the op rod) just as the bolt is in the last stages before closing. Almost like it has to "jump" over a little hump as the roller moves in the op rod groove. It is quite shiny in that area and evidence of peening on that little hump. It's almost like it was not properly cut, but without any drawing details (like the one found for the bolt on other sites) I cannot verify tolerances and compare.

4) This failure also appears the result of stress, but this time the force acting on the roller seemed to be almost direct. It would seem reasonable that the force from the spring would not be enough to do this. I suspect that the greatest force comes from the gas after firing, when the rod is pushing back violently and lifting the bolt from battery.

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5) I uploaded new pics. It is clear that the roller is not traveling on an even surface in the op rod groove, particularly on the "gas" stroke. The first failure could have been due to more stress being placed on one side of the clip versus the other. The second failure seems more like an impact. My op rod shows a definite wear in that regard, from pic #2.

6) How does my wear marks compare with others. Doc, your input would be valuable as you have seen so many of these things. Do you have any measurement/specs you can share? Either that, or this thing may be on it's way to the good Doctor.
 
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