Actually, for those whom are interested, I diagnosed the problem as a result of input from everyone AND observation of the behavior of the rifle.
You see, the oprod (from earlier pics) had impact (peening) inside the roller groove, particularly on the return to battery area (the area where the rod pushes the bolt along the receiver). That got me to thinking, but I dismantled the rifle prior to any kind of testing, and just ordered a new op rod because I could not find any reference dimensions anywhere. However, based on the Norky bolt, I did not exactly have a lot of faith in the Chinese attention to specification detail.
When I got the new oprod from DLASK, I was able to verify my intuition regarding the Norky Oprod. It likely worked fine because of the generous movement of the bolt, once in battery and the generous dimensions or the roller groove.
I was also able to TEST the new bolt and the new oprod in the rifle. Had to do some fitting to ensure the oprod moved freely and evenly until it passed the tilt test. When I moved the oprod/bolt to close in battery, I noted that the bolt would bind, or stop, if moved SLOWLY. The from lug of the bolt made contact with the barrel receiver. The roller was not however guided to move down to battery, rather it was "froze in time", so to speak.
That action results in compressive stress on the roller because the oprod would be impacting the roller at that point, rather than guiding it when the op rod is under spring tension. I inspected my mini14, and the oprod, indeed truly guided the roller into battery.
My new oprod sort of held it in place. I ever so gently removed a "ridge" in the groove, such that the roller would be guided into battery, rather than impacted. That did the trick. No matter howhard I tried, even with the new spring, I could NOT get the oprod to impact the roller.
For those of you whom are curious, check yours. Remove the spring and grease in the oprod roller groove. Open the bolt way back (without trigger assembly). Slowly move the bolt back along the receiver and closely watch the roller inside the groove. It should be fairly smooth and not "jiggle" too much.
He is where it gets good. Just before it goes into battery, see if it falls into battery. If it falls, because it is so slow, use your finger to prop it back up and check to see whether the oprod cradles the roller and "holds" it.
That was my mistake! My Nork bolt would fall into battery, because the lugs were smaller in width, when I moved it slowly. So did my new bolt. At real speed, under spring tension, the weight of the bolt was insufficient to move it quickly enough under the force of gravity and the oprod groove was cut such that it also "cradled" it. That caused the "slamming" of the bolt lug into the barrel receiver and the roller absorbing the full force of that impact.
I never noticed it until the second roller failure, because unlike the first, that one clearly showed it was an impact related failure. The new oprod, also had a negligible cradling effect with the norky bolt, but was really evident with the chinese receiver, new bolt and new roller. The fine grinding/sanding/polishing worked perfectly.
It is now a very smooth operating action. I learned by observation and listening what others wrote. Maybe it can help somebody else.
You see, the oprod (from earlier pics) had impact (peening) inside the roller groove, particularly on the return to battery area (the area where the rod pushes the bolt along the receiver). That got me to thinking, but I dismantled the rifle prior to any kind of testing, and just ordered a new op rod because I could not find any reference dimensions anywhere. However, based on the Norky bolt, I did not exactly have a lot of faith in the Chinese attention to specification detail.
When I got the new oprod from DLASK, I was able to verify my intuition regarding the Norky Oprod. It likely worked fine because of the generous movement of the bolt, once in battery and the generous dimensions or the roller groove.
I was also able to TEST the new bolt and the new oprod in the rifle. Had to do some fitting to ensure the oprod moved freely and evenly until it passed the tilt test. When I moved the oprod/bolt to close in battery, I noted that the bolt would bind, or stop, if moved SLOWLY. The from lug of the bolt made contact with the barrel receiver. The roller was not however guided to move down to battery, rather it was "froze in time", so to speak.
That action results in compressive stress on the roller because the oprod would be impacting the roller at that point, rather than guiding it when the op rod is under spring tension. I inspected my mini14, and the oprod, indeed truly guided the roller into battery.
My new oprod sort of held it in place. I ever so gently removed a "ridge" in the groove, such that the roller would be guided into battery, rather than impacted. That did the trick. No matter howhard I tried, even with the new spring, I could NOT get the oprod to impact the roller.
For those of you whom are curious, check yours. Remove the spring and grease in the oprod roller groove. Open the bolt way back (without trigger assembly). Slowly move the bolt back along the receiver and closely watch the roller inside the groove. It should be fairly smooth and not "jiggle" too much.
He is where it gets good. Just before it goes into battery, see if it falls into battery. If it falls, because it is so slow, use your finger to prop it back up and check to see whether the oprod cradles the roller and "holds" it.
That was my mistake! My Nork bolt would fall into battery, because the lugs were smaller in width, when I moved it slowly. So did my new bolt. At real speed, under spring tension, the weight of the bolt was insufficient to move it quickly enough under the force of gravity and the oprod groove was cut such that it also "cradled" it. That caused the "slamming" of the bolt lug into the barrel receiver and the roller absorbing the full force of that impact.
I never noticed it until the second roller failure, because unlike the first, that one clearly showed it was an impact related failure. The new oprod, also had a negligible cradling effect with the norky bolt, but was really evident with the chinese receiver, new bolt and new roller. The fine grinding/sanding/polishing worked perfectly.
It is now a very smooth operating action. I learned by observation and listening what others wrote. Maybe it can help somebody else.
