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Cam Pin/Benelli M4 Pictures?


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I'm curious how the cam-pins fare on these in the 10K+ round range. Stranger Danger? Any pictures? I know the cam-pin is an issue on the M4 (carbine) platform, and while I have never heard of it being one on a Benelli, I am just curious about the wear patterns.

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Why would there be any significant pressure on the pins at all ? The firing pin transits thru the cam pin in both 5.56 / M4 to keep it longitudinally oriented, their respective bolts are locked up with the barrel at the time of ignition....after ignition, they only serve to be a fixed point to rotate the bolt for extraction and feeding the next cartridge. If there was a any tension or pressure of significance, you would think it would manifest as a fractured firing pin as it is much smaller in diameter than the cam pin, that is being held in a right angle to the firing pin orientation, for the to-and-fro bolt to dance about. It would seem to be analogous to the firing pin retaining pin in both platforms, serving only to keep the firing pin within a certain limit of longitudinal travel.

Edited by benelliwerkes
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Why would there be any significant pressure on the pins at all ? The firing pin transits thru the cam pin in both 5.56 / M4 to keep it longitudinally oriented, their respective bolts are locked up with the barrel at the time of ignition....after ignition, they only serve to be a fixed point to rotate the bolt for extraction and feeding the next cartridge. If there was a any tension or pressure of significance, you would think it would manifest as a fractured firing pin as it is much smaller in diameter than the cam pin, that is being held in a right angle to the firing pin orientation, for the to-and-fro bolt to dance about. It would seem to be analogous to the firing pin retaining pin in both platforms, serving only to keep the firing pin within a certain limit of longitudinal travel.

This is typical wear for an M4 carbine cam-pin. Cam-pins in this platform should be changed when they are excessively worn, as they are a contributor to broken bolts (more wear = more slop = more shock)

 

After just 340 rounds:

campin23sj.jpg

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I just looked at the pin on a 13k+ cam for the M4. The only markings on it are polishing at the 9:30 and 4:30 position if you use the little marker point as the 12 o'clock position. This polishing is from the cam contacting the bolt carrier as it reciprocates. No dimensional changes were detected from the burnishing.

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I just looked at the pin on a 13k+ cam for the M4. The only markings on it are polishing at the 9:30 and 4:30 position if you use the little marker point as the 12 o'clock position. This polishing is from the cam contacting the bolt carrier as it reciprocates. No dimensional changes were detected from the burnishing.

 

nice

That is part of what I love about the Benelli M4 so much. It was engineered so well. I have yet to find a "fatal flaw" to it.

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