Pistol Primer problems - What caused this?

[SuperstitionCoues]

Hi.

I was firing off some CCI large pistol primers in 44 Mag brass (no bullets or powder, just empty case and primer) so that I could decap the brass and use it for a different load.  A couple, when fired, seemed to balloon backwards and expand, jamming the cylinder against the back wall of the pistol frame.  I had a heck of a time then indexing the cylinder around to eject the cases. 

What caused this, or what should I change in my loading techniques (re: primers) so that it doesn't happen with fully loaded ammunition?

Almost forgot...it was in a 7 1/2" SS Ruger Super Black Hawk.

[KN]

You don't have enough force to drive the brass back against the frame. When a round is fired, the first thing that happens is the primer backs out slightly. Then the preasure builds in the case and forces it back against the frame pushing the primer back flush into the pocket. Thats why "flattened" primers are a poor tool to judge high pressure by. They usually always look flattened to some degree. In your case the empty doesn't build any preasure and the primer stays backed out of the pocket locking up your gun. Your brass may also have loose pockets that are exagerating the problem.   KN

[cwlongshot]

KN is correct.

 I have two questions....  Why do you do this and is it a regular thing?

 If its something you do allot. You could alter brass so its less likely to have the primers back out.
 Years ago, I shot allot of wax bullets for practice at home in the basement. They are powered by primers alone so are lo velocity and safe for basement use. You need to alter the brass by opening up the primer FLASH HOLE. Doing this keeps the "pressure" down in the primer pocket. Which in turn lessens the possibility of the primer backing out.

 CW

[Savage]

Well, two excellent and concise answers to the question. Nothing to add there. One question tho, do you use different primers for your various pistol loads? I can see that in loading rifle loads for best accuracy, but it is doubtful that changing a primer brand would make a significant accuracy difference in a straight wall pistol case. With all my SW pistol cases I use one brand of primer, and work up loads accordingly.  You may have reason to do otherwise, but I like to keep it simple.
Savage

[SuperstitionCoues]

I was firing off the primers in open, "blank" cases because I had set them up in a reloading block a few months ago, the label fell off by the time I could get back to them (last week), and by then I honestly couldn't remember what brand or size I had put in there.  Obviously I didn't want to use an unknown in live ammo, let alone work up a load that therefore worked and I couldn't duplicate it.  So, no, it isn't a regular thing and I am very new to the pistol side of things.

So the brand of primer, unlike rifle ammo, doesn't make that much difference in pistol ammo?