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Posted: 7/2/2008 8:52:49 PM EDT
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Guys...sorry if this is the wrong topic for here.....but.....when clearing my Bushmaster V Match...I noticed the primer in the rounds..ejected from the chamber...has dimples in them from the firing pin hitting them?? Now...this is reloaded ammo...inwhich I am very conscientious on loading safe ammo... I know that the ARs have the floating firing pin and I am very careful to seat primers below flush to pervent slam fires....These primers in photos are seated from .004" to .002" below flush. The primers are CCI Bench Rest. Is this typical that the firing pins in ARs dimples the pimers as such??? Thanks for the help.... http://i123.photobucket.com/albums/o312/hainespd/primers-1.jpg http://i123.photobucket.com/albums/o312/hainespd/primers-1-1.jpg |
Yes |
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Looks normal to me. On a new weapon, to check if the primer dimple is "excessive"... Without a magazine inserted in the weapon I lock open the bolt, single load a round into the chamber and ensure it's all the way seated in the chamber by pointing the barrel at a slight downward angle. (While pointed downrange of course) Once the round is chambered, I depress the bolt catch and allow the bolt to slam home. If the weapon fires, it's obviously excessive, if the dimple seems excessive, light honing on the firing pin may be warranted. If it's dimpled but not excessive and no discharge- good to go. Those pics are great and this should be tacked to help newbies. Sly |
| What actually causes the dimple from just chambering is the firing pin is pretty much free floating with no springs holding it back. Because nothing is holding the pin in place when the BCG slams forward, the inertia causes the pin to hit the primer just enough to cause that tiny dimple. Think about it about the same as if you were to drop a nail on a piece of wood vs using a hammer to pound the nail into the wood. Generally, unless some very odd situation happens, its very normal and not dangerous (as long as you always follow the rules of gun safety). As others have said, it doesn't look out of the ordinary. |
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Whew!!!! You guys are the bearer of good news for sure hank In reloading for the ARs...I asume there are brands of primers to stay away from?? I hear Federal primers have soft cups.....May be dangerous to use these types of primers? |
I wouldn't say dangerous. I have had Federal Factory 68gr HPBT's slam fire on me. Only happened twice, first time I almost blew off my foot, second months later sounded like a fast controlled pair. 
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I also have 2 M1 garands and reload for them. They also have the floating firing pin. Was told that the federal primers has a very soft cup so I stay away from them in the M1s and my Bushmaster. You guys that has had slam fires in you ARs....Ah...no injuries and torn up rifles? I always thought slam fires can be pretty catastrophic |
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I heard of military small rifle primers, they have a thicker cup to reduce the chance of slamfires. I also heard these were recommended for use with the AR-15. Now I have two AR's that don't use small rifle primers, and there isn't military large rifle or large pistol primers on the market, so am I at more risk for a slamfire with these cartridges? That being said, i've been using federal no. 200 primers for my .223 loads. Federal no. 200 and Winchester Large Rifle for the 6.8 SPC(ssa and remington brass), and Winchester Large Pistol for the .458 SOCOM. I have yet to experience a slam fire with any of these cartridges. When I initially loaded up my ammunition for the .458 SOCOM I had 3 pierced primers, but after that it didn't happen anymore. A retention spring for the firing pin would really be peace of mind though I question whether it would actually work or not. I think they have something like that for the AR-10. |
ARs will only slam fire this way in near full battery, as the firing pin won't protrude far enough until then |
I would like to add, even the bolts with a firing pin spring will dent primers. My Oly 9mm upper had a firing pin spring and it would still dent the primer. Thanks, Wesley |
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