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Posted: 7/30/2011 6:26:27 PM EDT
Thought I had a round stuck in the chamber since I couldn't eject the brass at all, this was during competition, and locked the bolt back and took out the barrel to see if I could remove the casing that way and when I looked at the chamber I noticed the casing wasn't in there anymore and bent over to look for it on the ground and noticed this part laying on the ground next to the casing. 
Besides getting a new bolt what else should I look for that's fubar'd on my rifle?
Less than 3K rounds through her for those that want to know. |
I had a cam pin shatter and my E4 kept on running. After discovering it (upon cleaning) I just replaced the cam pin with a stainless one I got from Ratworx. My bolt looked fine but yours should be replaced because the cam pin hole looks streatched and there is that big chunk taken out of the bolt behind the extractor. That is now my spare bolt as I purchased the Hybrid bolts for both my E4's. MadDog |
Here's a pic from the archives ,side by side MSAR and AUG carriers, compare them to yours. I think youirs should be checked carefully with a new bolt to make sure the timing is correct. Its possible your cam pin just went bad and ruined the bolt , again how the bolt is unlocking from the trunnion while it travels in the carrier should be checked ,you never know the broken cam pin may have caused damage to the carrier slot. Call Ratworx.
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| Wow! This is a catastrophic failure. Your bolt failed because of the wallowing out of the bolt carrier slot, which is ruined BTW. The stresses applied to the cam pin were eventually overcome and most likely sheared when the bolt fragment splintered. The cam pin acted like an impact hammer on the casting of the carrier slot because it is harder steel but it too eventually failed probably because it was slamming back and forth on the bolt body and the carrier slot. Also your cocking piece is fractured. What need to be determined is why did the carrier deform? The bolt sleeve is what prevents this when cycling. It does not look from the pics that the sleeve is damaged but if that deformed first then the carrier slot deformation would follow. If not, something else is afoot. |
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Quoted:
Wow! This is a catastrophic failure. Your bolt failed because of the wallowing out of the bolt carrier slot, which is ruined BTW. The stresses applied to the cam pin were eventually overcome and most likely sheared when the bolt fragment splintered. The cam pin acted like an impact hammer on the casting of the carrier slot because it is harder steel but it too eventually failed probably because it was slamming back and forth on the bolt body and the carrier slot. Also your cocking piece is fractured. What need to be determined is why did the carrier deform? The bolt sleeve is what prevents this when cycling. It does not look from the pics that the sleeve is damaged but if that deformed first then the carrier slot deformation would follow. If not, something else is afoot. I don't know if you have an AUG or not, but if you do I suggest you take it apart and watch the BCG function....it does not function as you describe. The sleeve prevents the bolt from rotating until the last possible second, much like the cut in an AR upper receiver to allow the cam pin to rotate. Did you happen to look at the case that fired right before the failure? Any signs of overpressure? Your bolt failed most likely due to fatigued stresses overtime while the BCG was opening. A higher than normal round fired on the high gas pressure could have caused a carrier speed that would have sufficient force to break the camels back. Once the bolt failed your cam pin was just collateral damage. Your carrier looks pretty banged up but that could have occurred during the event or if it was machined improperly, it could have led to the higher than normal stresses and ultimate failure. Interestingly enough, my cocking plate is also cracked, in the exact same manner. This is most likely from the firing pin impacting the cocking plate during firing (primer pressure or just inertia). It will still function as long as it all snaps in place but since I am assuming everything else will be replaced, get another. I take back my original assessment of a nitrided bolt, it looks like a parked bolt when I compare it to mine. More reason to  it should be pretty strong. Is the right hand thrust piece (part that the piston impacts) mushroomed at all?
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Quoted:
Quoted:
Wow! This is a catastrophic failure. Your bolt failed because of the wallowing out of the bolt carrier slot, which is ruined BTW. The stresses applied to the cam pin were eventually overcome and most likely sheared when the bolt fragment splintered. The cam pin acted like an impact hammer on the casting of the carrier slot because it is harder steel but it too eventually failed probably because it was slamming back and forth on the bolt body and the carrier slot. Also your cocking piece is fractured. What need to be determined is why did the carrier deform? The bolt sleeve is what prevents this when cycling. It does not look from the pics that the sleeve is damaged but if that deformed first then the carrier slot deformation would follow. If not, something else is afoot. I don't know if you have an AUG or not, but if you do I suggest you take it apart and watch the BCG function....it does not function as you describe. The sleeve prevents the bolt from rotating until the last possible second, much like the cut in an AR upper receiver to allow the cam pin to rotate. I have a STG-556 and am well aware of the sleeve function. Yes it keeps the bolt from rotating until the last moment but it also acts as a reinforcement guide for the cam pin to actuate with and it has a more precise track than the carrier casting surface. The slot in an AR carrier is in machined steel as opposed to a casting and thicker and the cam inserts from the top into the bolt and it possess an integral collar that allows the cam to reciprocate so a spring loaded sleeve is not needed. The setup(cam pin) is opposite in the AUG platform. The AR setup also contains the gas containment system on the bolt itself and on the AUG the spring loaded sleeve allows the bolt to reciprocate until the sleeve fingers contact the barrel extension compressing the spring while allowing the bolt to continue into the barrel extension whence it rotates. |
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Quoted:
This scares the hell out of me and makes me not want to shoot my MSAR's! I kind of like my face where it is! Anyone ever hurt by an MSAR or AUG exploding that you remember? It has been discussed here several times and no one has ever come up with any evidence of this ever happening. |
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Quoted: Quoted: This scares the hell out of me and makes me not want to shoot my MSAR's! I kind of like my face where it is! Anyone ever hurt by an MSAR or AUG exploding that you remember? It has been discussed here several times and no one has ever come up with any evidence of this ever happening. If anyone ever does, please believe me when I say that I will tack the thread as that would be important information for all who own them to know (me included). |
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Got my new bolts today and she's back together.
Got an MSAR bolt, warranty, and also the hybrid bolt. Note. When putting your rifle back together don't lock the charging handle back and leave your thumb in the way in case the handle is knocked loose trying to get the reciever back into the stock and slams into your thumb.    
There is "Garand thumb", now I introduce MSAR thumb.
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