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Posted: 5/6/2006 4:27:52 PM EDT
| I`m confused, i`ve got two ar-15`s with the same uppers (cmmg 16" M4ery`s) one is on a bushmaster w/skeleton stock (full size) and the other one on a dpms carbine lower. While shooting adcom M855 ammo the dpms blows primers almost every other shot and the bushy eats them up with no problems. Why is this? Could it be the buffer in the carbine is to lite? Any help would be greatly appreciated.-Todd |
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If the primers are falling out of the case intact it is an overpressure problem. This has nothing to do with the firing pin or buffer. Perhaps the rifle has a commercial 223 Remington chamber or the bore is undersize, hard to know without seeing the rifle. Cheers, Phil |
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Repeated pierced primers will flame cut your firing pin, enlarge the firing pin hole and flame cut your bolt face. Stop shooting until you figure out what the problem is and then, at a minimum change out your firing pin. If the firing pin hole is enlarged, bite the bullet and get a new bolt, because it is never going to get any better. |
My guess, and it's just a guess, is improper head spacing. I've never really tackled any headspacing problems to date but my interpretation is if the headspacing is too great, the primer gets blown out of the pocket as it comes back to meet the bolt face. How many rounds on the DPMS? Was the bolt factory matched to the barrel to ensure proper headspacing? Sly I'll leave my interpretation open for correction if necessary. 
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+1 Maybe short in the throat area? |
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sounds like you got a head space problem. First get some 223 rem. ammo NOT 5.56 nato. IF still dose same. Heads up their is 3 typs of chambers for 223. First is the small 223 rem. Next up is wilder (hope I got it right). This chamber size will shoot both rounds good. Largest and last is 5.56 nato. Check chamber size and shoot proper ammo. If this dosn't work get some head space guages and go from their! |
Is the Adcom dated 99? If it is blown primers have been common. I have some that blows more out with a carbine than a rifle, but it still does it ocassionally with the rifle. |
Yes it is, i have read that several people have had problems with this ammo. I`m just confused why it works great it one rifle but not the other, next weekend i`m going to swich the uppers to see if the problem is with the upper or the lower. The cmmg upper/dpms lower eats everyother type of ammo with no problems (just the adcom M855) and am almost out of it and will not buy it again.-Todd |
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