Are small magnum pistol primers harder than small pistol primers?

[Tennessee Jed]

I've been handloading 357 magnum for a couple of years now. I just recently noticed that the recipes I got from Accurate Arms for AA9 in 357 mag called for magnum small pistol primers, and I'd been using small pistol primers.

So over the weekend I fired 50 of the old rounds with small pistol primers, and had no issues. I then fired 50 rounds that had the magnum small pistol primers and had about 3 misfires. The gun was a GP100 that's never misfired before. I previously used CCI small pistol primers (#500), and on this batch started using the CCI magnum small pistol primers (#550).

It's not a huge thing, and the rounds fired on a second try, but I HATE hearing a click when expecting a bang. The only thing I can figure is that the 550's are harder than the 500's. Is it possible that the 550's are harder?

[Misssissippi Dave]

It is possible the magnum primers are harder. It is also possible the primers were not fully seated as well. I normally use Federal or Tula magnum primers in my .357 loads with AA7 powder. It doesn't call for a magnum primer with the load data I used. I suggest making certain all the primers are fully seated and try another 50 to see if that may have been the problem. The only time I can see needing a magnum primer in .357 is very cold weather or using H110 or Winchester 296 powder. Possibly HS-6 and HS-7 as well. Accurate's data does list a magnum primer with AA powders but Spear only notes it for a few powders. I sure other referrences will vary too.

[Brian Pfleuger]

It's not a huge thing, and the rounds fired on a second try, but I HATE hearing a click when expecting a bang. The only thing I can figure is that the 550's are harder than the 500's. Is it possible that the 550's are harder?

CCI Magnum pistol primers are reportedly identical to their small rile primers in every respect. The cup is slightly thicker than the small pistol, by about 0.005 IIRC.

In any case, fired on the second attempt is a very good indicator that they weren't seated deep enough. The first strike finished seating them, the second fired them.

[Hammerhead]

How do you seat your primers?

I started having trouble with my new GP100 when I switched to Tula primers. I was priming on the press mounted primer arm.
I switched to the RCBS Ram prime and the problem disappeared. I must have been leaving some primers slightly high.

[steve4102]

fired on the second attempt is a very good indicator that they weren't seated deep enough. The first strike finished seating them, the second fired them.

This would be my guess as well.

[Tennessee Jed]

I've been using my Lee Classic Turret press to seat the primers. Sounds to me like I need to pay closer attention to making sure the primers are seated deeply enough. Thanks you all for your help.

[rclark]

This would be my guess as well.

Ditto.... Although the slightly thicker cup also contributes.... CCI have the hardest cups out there I understand with Federal being the softest.

That's what I like about using my RCBS hand primer. You 'feel' the primer hit bottom and then a slight squeeze more to 'set'. I wouldn't be without one now.

[mikld]

http://www.sksboards.com/smf/index.p...;topic=56422.0

A good read on primers...

[jersurf101]

My Taurus 669 has a hard time hitting CCI 550's hard enough to set them off. No problem at all with CCI 500's. I haven't used any other magnum primers to see the difference but CCI 550's are definitely harder