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Posted: 11/16/2011 3:37:53 PM EDT
| I have two CMMG dedicated firing pins..One has a rounded end and one a flat end where the hammer stikes..Is one a older version maybe? If so which is the newer one...Thanks |
| I believe the sharp corners would exist wether a flat or rounded head but maybe the idea behind the flat VS the rounded is the flat of the hammer would be striking a completely flat area of the head on the pin and maybe that would translate to a more solid impact having two same surfaces working with eachother rather than with the rounded head where you would be striking a minimal area..Not sure though on that maybe it would be the opposite effect..Also maybe it is just more stressful with a flat hammer striking a very small area on a rounded head that may stress the corners more...Just thinking outloud...Thanks |
| My understanding from my conversations with CMMG is that the main update in the CMMG firing pin was done in the area of the cut-out when the firing pin retaining cotter pin goes. The original design was a straight cut which left a very square little corner in the pin. This left a stress concentration area which allowed the pins to break. The new design pins have rounded "corners" in that area to relieve the stress and are therefore far less likely to break. If you look at a firing pin you see that cut out is the weak point in the pin. As for the other changes, I would just guess that when they were redoing the design they spec'd out other tweaks to address any other issues while they were at it. I know my older .22 bolt has a rounded end where the hammer hits it and it has been humming along for many years with out issues. But, that may be a function of the nice rounded DPMS hammer I have used with it. |
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Quoted:
LOL. Ditto! Still, we have 2 posters that had broken rounded pins, and none for the squared pins. Things that make you go hmmmm.....  Mine broke at the transition from the larger diameter to the smaller diameter toward the front of the firing pin. The broken pin does not appear to have a radius and the new one does have a radius so it would be more likely to break. The rear of the pin wouldn't have much affect on that |
| You guys are right on and I never even noticed the differance..The newer style is radiused in the center notch,at the rear at flat head and at the point where the firing pin tip is turned down..Wow I need some new glasses...CMMG told me the old style can break and they have in the past quite often...Thanks |
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Quoted: Ok. Well that makes sense to me. I just pulled the pin on mine to have a look. Nice sharp corners everywhere. My understanding from my conversations with CMMG is that the main update in the CMMG firing pin was done in the area of the cut-out when the firing pin retaining cotter pin goes. The original design was a straight cut which left a very square little corner in the pin. This left a stress concentration area which allowed the pins to break. The new design pins have rounded "corners" in that area to relieve the stress and are therefore far less likely to break. If you look at a firing pin you see that cut out is the weak point in the pin. As for the other changes, I would just guess that when they were redoing the design they spec'd out other tweaks to address any other issues while they were at it. I know my older .22 bolt has a rounded end where the hammer hits it and it has been humming along for many years with out issues. But, that may be a function of the nice rounded DPMS hammer I have used with it.  I guess it's possible that the square head pins serve to address a different issue -or- maybe it's just a way for them to quickly identify the newer design firing pin vs. the older non-radius cut pins. I guess I'll order myself a spare now to keep on hand, to avoid down time later. Sigh.....   |
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