Check this out:
Here are the details:
I was loading 9MM on a Dillon 1050 (subsonic 147s). The brass is mixed, but includes some outdoor range pickups from shortly after the snow melted. For those of you that don't know this, the snow melt yields a ton of brass. Everything people shot during the winter that ended up on the ground suddenly becomes visible.
Here's why it happened
Take a look at the closer photo below. When the sizing die decapped the case, it didn't remove the whole primer. Instead, it punched out the bottom of the primer and left the sides of it stuck in the primer pocket. I attribute this to corrosion during the period the brass sat under the snow.
Unlike most other presses, the Dillon 1050 primes the case at the bottom of the downstroke. The 750, 550, LNL, RCBS 2000, Square Deal B and others prime the case when you push forward on the handle when it's all the way up. If the 1050 worked like this, I would've felt resistance and stopped. Since the 1050 primes at bottom, you can't feel the primer go in over the force of sizing, swaging, seating, and crimping.
The bottom of the exploded primer is stuck inside it, but broken off (I poked the bottom disk out after I took the photo). The priming anvil is smaller in diameter than the primer. When the press tried to insert the new primer, the remaining portion of the old primer prevented it from seating. The primer anvil pushed hard enough on the bottom of the new primer to break it out with enough velocity to set it off.
It happened a couple of times. I'm not sure if I should decap this brass separately or just keep going and wear ear plugs.
The lesson here is if you have wet brass, dry it, and be careful with cases that sat under the snow for a season.
Here are the details:
I was loading 9MM on a Dillon 1050 (subsonic 147s). The brass is mixed, but includes some outdoor range pickups from shortly after the snow melted. For those of you that don't know this, the snow melt yields a ton of brass. Everything people shot during the winter that ended up on the ground suddenly becomes visible.
Here's why it happened
Take a look at the closer photo below. When the sizing die decapped the case, it didn't remove the whole primer. Instead, it punched out the bottom of the primer and left the sides of it stuck in the primer pocket. I attribute this to corrosion during the period the brass sat under the snow.
Unlike most other presses, the Dillon 1050 primes the case at the bottom of the downstroke. The 750, 550, LNL, RCBS 2000, Square Deal B and others prime the case when you push forward on the handle when it's all the way up. If the 1050 worked like this, I would've felt resistance and stopped. Since the 1050 primes at bottom, you can't feel the primer go in over the force of sizing, swaging, seating, and crimping.
The bottom of the exploded primer is stuck inside it, but broken off (I poked the bottom disk out after I took the photo). The priming anvil is smaller in diameter than the primer. When the press tried to insert the new primer, the remaining portion of the old primer prevented it from seating. The primer anvil pushed hard enough on the bottom of the new primer to break it out with enough velocity to set it off.
It happened a couple of times. I'm not sure if I should decap this brass separately or just keep going and wear ear plugs.
The lesson here is if you have wet brass, dry it, and be careful with cases that sat under the snow for a season.