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Old October 22, 2012, 09:41 AM   #4
Unclenick
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Join Date: March 4, 2005
Location: Ohio
Posts: 10,206
TMD,

Your response is a common one, but it's still just anecdotal evidence as the next guy's gun may not have the same relationships between chamber, boltface and firing pin protrusion as yours does. Also, I've counted slamfires at big matches before and estimated there seem to be about one for every 15-20,000 rounds downrange or so. Assuming that number applies to non-match guns as well as match guns, you'd have to shoot through a couple or three AR barrels to have an even chance of having one, so maybe you just haven't had your turn yet.

I shot the sensitive Federal 210M in Garands and an M1A for years without an incident, so you'd think I'd share your thinking on this, but I no longer use them in those applications. I look at slamfires and out of battery fires like head-on collisions in cars. I've never had one, but that doesn't mean they can't happen or that measures to reduce their likelihood, like dividing highways, won't prevent some. I don't want to be in the position of having one of the rare OOB fires that injures a junior shooter on an adjacent firing point and not think I'd taken every prudent precaution to avoid it. I also don't want the attorneys his parents hire discovering I haven't taken every known possible preventive measure to prevent its occurrence.

The CCI #41 is identical to a CCI 400 magnum small rifle primer, except that the anvil is shorter so more firing pin crush is needed to set it off.

The TulAmmo KVB556M is a much less expensive Russian made NATO spec primer. I don't know the mechanism of sensitivity control in those, but can tell you they give me lower velocity extreme spread than the #41's do. They take a little more force to seat, but otherwise are great performers. They are also a magnum primer.

The new entry in the field is the Federal GMM205MAR, which is not a magnum primer. An email to Federal got me the information that it is identical to their mild and very consistent GMM205M, except that they've made the cup thicker as their sensitivity control.

So you have three to choose with cheap to expensive pricing.
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