Small CCI SP primers

[1Shirt]

Have been using SP primers for Hornet and K-Hornet. This morning I had 3 cases (Winchester Brass/CCI SP primers), loaded with 5 gr. Unique under 225438HP, that blew the primer out of the case. Have used same brass with both Win and Rem SP primers, and same load with no problem. Ambient temp was about 85 degrees, and I shot about 15 of these loads of which the three were in that batch. Has any one else experianced this problem with CCI small pistol primers?

Thanks to all who respond to this thread.
1Shirt!

[44man]

There is something else going on. I don't think I would blame the primer.
Was the primer pocket over expanded? SEE event. Head space problem?
Yes, even a fast powder with too much air space can reverse pressure if the boolit stutters at the rifling. Does the chamber have a long lead?

[1Shirt]

44 Man, Primer pocket not over expanded. I pulled the rest of the loads, and deprimed all of the cases that were loaded, and resized and deprimed the ones that I had shot. There was normal resistance in loading Fed Small Pistol primers, and will load and shoot same with same load next time I go to the range for comparison. Rifle is a M-40 Sav. single shot bolt action. The cases where the primers did not come out showed no signs of excessive pressure. (for what ever that is worth) Chamber does have a long lead. I had seated to factory length specs. Will seat longer on the next batch just shy of the lands. The CCI SP primers were quite old, probably 5-7 years bud doubt that that had anything to do with it. Thanks for the reply.
1Shirt!

[dragon813gt]

I have not had any issues. I recently received a bunch of older primers that date back to into the 80s and they all loaded and shot fine.


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[Rocky Raab]

If I understand correctly, even the cases where the primer came out showed normal primer seating pressure (with different primers) afterwards? If so, your thought about a few undersized CCIs might well be valid. That's extremely doubtful, but nothing is impossible.

(Even primers from the 80s aren't truly old. I have and use Western 1½ small pistol primers that were made in the 50s. They're actually some of the most accurate in my Hornet rifle!)