Another bolt roller failure... FML
- Thread starter chemo
- Start date
Rocket Surgery
CGN Ultra frequent flyer
I know I'm not a gunsmith, but could it perhaps be the machining on the receiver? Maybe it's off by a bit and putting stress on the roller?
If it's not the oprod or bolt, what else?
Chemo did you purchase the gun from a shop that has a 1-year or 5-year warranty? I'm sure you could just get another gun.
If it's not the oprod or bolt, what else?
Chemo did you purchase the gun from a shop that has a 1-year or 5-year warranty? I'm sure you could just get another gun.
When did I inspect her, on my bench? At a clinic? I'm curious now hehehe.
In the past 5 years I have seen 2 chinese rifles throw their rollers.
This issue is more commonly found with springfield M1A rifles due to a also common receiver machining flaw. I've never seen or heard of a chinese receiver with the common SA receiver flaw.
3 locations to inspect would be right behind the receiver's right lug pocket, inside the oprod's roller pocket and the roller stud itself.
Curious to know how many rounds on the roller and what ammo was typically used and what ammo was used when the failure occured. Is this the first time this has happened in this rifle?
In the past 5 years I have seen 2 chinese rifles throw their rollers.
This issue is more commonly found with springfield M1A rifles due to a also common receiver machining flaw. I've never seen or heard of a chinese receiver with the common SA receiver flaw.
3 locations to inspect would be right behind the receiver's right lug pocket, inside the oprod's roller pocket and the roller stud itself.
Curious to know how many rounds on the roller and what ammo was typically used and what ammo was used when the failure occured. Is this the first time this has happened in this rifle?
I am by no means an expert on rollers....but I have had some experience with the whole issue (see previous posts) and the solution was surprising.
In my case I replaced my Norky bolt with a USGI. After about 20 to 30 rounds of factory rounds, the roller either split longitudinally or like yours.
Y'know what I believe the problem ended up being? The op-rod. I continued to use my Norky op-rod with the new bolt and blew rollers. I bought a usgi op-rod and blew a roller.
I inspected the op-rod very closely, and put it through it's paces with no spring loading. You see, with my basic metallurgy and structural analysis courses and experiences, I realized that when you get right down to it, the roller itself, within the confines of the op-rod, is really not designed to absorb tremendous stresses. In my rifle, when the op rod was guiding the roller (bolt into battery position) the bolt itself was tight against the barrel, and the cut groove in the op-rod was shaped like a cup. In effect, the op rod was holding/carrying the bolt (via the roller) until it slammed against the breech, and then it was forcing into battery by overcoming the little holding "hump" and area of high stress (point loading) to say the least.
My solution, I took a very fine grinding stone on my dremmel and reshaped the inside such that the roller, once into battery and resting against the breach was now "guided" into battery with a refined channel. No hump, no bump...only a smooth transitional groove.
The USGI op-rod had a gentler slope than the Norky op-rod.
This was the Norky after a failure with new bolt. Note the shiny "pounded" area where the op-rod struck the bolt roller to open it. There was a distinctive hump and irregular wear inside the guide area. On the USGI op-rod, the wear was fairly uniform.
It is hard to see, but you can see the way the rear of the guide sort of "cups" or holds the roller. This was an area on both op-rods where there was evidence of pounding. This was the location where I carefully ground down the hump. The result was that the op-rod gently guided the roller into the sloped part, which then allowed the roller to be guided into battery, rather than slamming it into battery.
I have not had a problem since, and am back to using my 150 gr reloads, which are loaded to the USGI spec for velocity.
In my case I replaced my Norky bolt with a USGI. After about 20 to 30 rounds of factory rounds, the roller either split longitudinally or like yours.
Y'know what I believe the problem ended up being? The op-rod. I continued to use my Norky op-rod with the new bolt and blew rollers. I bought a usgi op-rod and blew a roller.
I inspected the op-rod very closely, and put it through it's paces with no spring loading. You see, with my basic metallurgy and structural analysis courses and experiences, I realized that when you get right down to it, the roller itself, within the confines of the op-rod, is really not designed to absorb tremendous stresses. In my rifle, when the op rod was guiding the roller (bolt into battery position) the bolt itself was tight against the barrel, and the cut groove in the op-rod was shaped like a cup. In effect, the op rod was holding/carrying the bolt (via the roller) until it slammed against the breech, and then it was forcing into battery by overcoming the little holding "hump" and area of high stress (point loading) to say the least.
My solution, I took a very fine grinding stone on my dremmel and reshaped the inside such that the roller, once into battery and resting against the breach was now "guided" into battery with a refined channel. No hump, no bump...only a smooth transitional groove.
The USGI op-rod had a gentler slope than the Norky op-rod.
This was the Norky after a failure with new bolt. Note the shiny "pounded" area where the op-rod struck the bolt roller to open it. There was a distinctive hump and irregular wear inside the guide area. On the USGI op-rod, the wear was fairly uniform.
It is hard to see, but you can see the way the rear of the guide sort of "cups" or holds the roller. This was an area on both op-rods where there was evidence of pounding. This was the location where I carefully ground down the hump. The result was that the op-rod gently guided the roller into the sloped part, which then allowed the roller to be guided into battery, rather than slamming it into battery.
I have not had a problem since, and am back to using my 150 gr reloads, which are loaded to the USGI spec for velocity.
I have no more time to waste with this POS
i'll give you $100 for the complete rifle!
I sent it to you in summer of 2010 (to replace a new roller, cut and install muzzle break, complete inspection), since then I have only shot 150gr pills using minimal ammount of BLC-2 (45.0 grains) and norinco ammo recently imported by canam (which are the rounds I shot last). round count is as displayed in first post
The kind that is cleaned up before taking a picture.
But seriously, I use snowmobile grease. Great range of temperature stability. Had to clean it because all that grease makes it hard to inspect
