Punctured primers

► A lot of punctures with target loads are attributable to the firing pin going too deep.

► A lot of high pressure (or "full house") loads should be using a primer with a thicker cup.

I don't think anyone here can help you until you tell us about your load and the brand of primer you're using.

need more info: weapon used, ammo description (factory or reload, bullet size and type, etc.), rounds fired since last cleaned, etc.

murf

Are you using large rifle primers? Are cases made for LRP? Are you using heavy bullets?

This form Starline.

The Initial run of 500 S&W Mag cases was built to use large pistol primer per Smith & Wesson and Cor-bon specifications. On July 28, 2003, Smith & Wesson and Cor-bon changed specification of primer pocket to be large rifle. Rifle primers are same diameter as pistol except they are approximately .006" taller. This was done to prevent primer from being pierced by firing pin when loaded with max loads and heavy bullets (bullets over 400 grains). It was determined that hole in primer allowed pressure to damage firing pin and bushing, kind of like a cutting torch and the harder cup of a rifle primer will prevent occurrence. All cases sold by Starline, Inc. after July 28, 2003, will contain a large rifle primer pocket to accept a large rifle primer.

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I had a S&W Model 610 do the same thing. It turned out to be the firing pin bushing, which had to be replaced by the factory. Once they replaced the bushing, the problem went away.

Hope this helps.

Fred

Picture of the primers? In my opinion there are three different say-na-eros. The first big dent is a primer that did not get crushed as in it did not have enough bang to conform to the firing pin. Pressure inside the primer forces the primer dent out and in doing so it forces the primer to conform to the protruding firing pin.

Then there are the two in the center, normal, the primer was crushed then the pressure inside the primer forced the primer to conform to the shape of the firing pin.

Then the last one, the one with the hole in it, that primer worked as designed but when the pressure inside the primer forced the primer to conform to the firing pin the spring (mechanical means of operation) was not strong enough to overcome the pressure inside the primer, when this happens the pressure inside the primer pushes the firing pin back. When this happens the breach face days are numbered because of the hot high pressure metal cutting gas escaping out the rear of the case cuts a big hole in the breach and or bolt face.

The primers show definition around the perimeter of of the primer, high pressure would have flattened the edge of the primer.

F. Guffey

Two thoughts, one, the case/powder and bullet out runs the firing pin to the front of the chamber, or. two, the firing pin crushed the primer, then everything gets busy and in a very short (few) milliseconds including barrel time it is over.

Then there is the crater: A dent in the center surrounded by a high wall, something like a crater. In my opinion the hole in the last primer is without a crater. But, if you do not want hot high pressure metal gutting gas escaping from the primer rethink your methods and or techniques.



F. Guffey

Cut your loads. If you are piercing primers the pressures are too high for your primers.

Looked at your firing pin? Pierced primers will dish firing pins.

Magnum Shooter said:

Are you using large rifle primers? Are cases made for LRP? Are you using heavy bullets?

This form Starline.

Click to expand...

Those primers do look pretty deep down in those holes. kinda get dizzy looking at that fuzzy picture though