Variance in primer size

Gary L. Griffiths · October 25, 2014, 01:26 AM

Last night I reloaded some twice-fired LC-13 cases with CCI-41 and CCI-400 primers to test different loads. I found, to my surprise, that the CCI-41s slipped easily into the primer pocket, with almost no resistance. Now, an enlarged primer pocket is usually a sign of very high pressure, but all of this brass had been loaded with fairly mild loads. Some of the cases were so loose that I was able to deprime them by hand!

I finally found 25 cases that retained the primers adequately, then, just for gits and shiggles, I tried priming the "too loose" cases with CCI-400 primers, and they all primed with what I consider "normal" resistance. So I miked the primers, and found that the CCI-400s uniformly measured 0.175" in diameter, while the CCI-41s uniformly measured 0.174"

I don't know whether the batch of 41s that I bought are slightly out-of-spec, or whether they are manufactured smaller, perhaps to facilitate crimping.

Just wondering if anyone else has experienced this phenomenon?

Snyper · October 25, 2014, 06:48 AM

Quote:

I don't know whether the batch of 41s that I bought are slightly out-of-spec, or whether they are manufactured smaller, perhaps to facilitate crimping.

They could just be at the low end of the allowable tolerance, although the crimp theory sounds logical too

1MoreFord · October 25, 2014, 10:30 PM

Years ago when I first started reloading I used CCI primers and a Lee hand priming tool. The first time I bought WW primers I thought something was wrong when they seated so easily. After I realized the WW and Federal primers worked fine and the CCI primers were either oversized or had way too thick cups I never used CCI again. YMMV

October 25, 2014, 01:26 AM	#1
Gary L. Griffiths Senior Member Join Date: April 8, 2000 Location: AZ, WA Posts: 1,469	Variance in primer size Last night I reloaded some twice-fired LC-13 cases with CCI-41 and CCI-400 primers to test different loads. I found, to my surprise, that the CCI-41s slipped easily into the primer pocket, with almost no resistance. Now, an enlarged primer pocket is usually a sign of very high pressure, but all of this brass had been loaded with fairly mild loads. Some of the cases were so loose that I was able to deprime them by hand! I finally found 25 cases that retained the primers adequately, then, just for gits and shiggles, I tried priming the "too loose" cases with CCI-400 primers, and they all primed with what I consider "normal" resistance. So I miked the primers, and found that the CCI-400s uniformly measured 0.175" in diameter, while the CCI-41s uniformly measured 0.174" I don't know whether the batch of 41s that I bought are slightly out-of-spec, or whether they are manufactured smaller, perhaps to facilitate crimping. Just wondering if anyone else has experienced this phenomenon? __________________ Violence is an ugly thing, but not the ugliest of things. The decayed and degraded state of moral and valorous feeling which believes that nothing is worth violence is much worse. Those who have nothing for which they are willing to fight; nothing they care about more than their own craven apathy; are miserable creatures who have no chance of being free, unless made and kept so by the valor of those better than themselves. Gary L. Griffiths (Paraphrasing John Stuart Mill)

October 25, 2014, 10:30 PM	#3
1MoreFord Senior Member Join Date: July 30, 2014 Location: Arkansas Posts: 244	Years ago when I first started reloading I used CCI primers and a Lee hand priming tool. The first time I bought WW primers I thought something was wrong when they seated so easily. After I realized the WW and Federal primers worked fine and the CCI primers were either oversized or had way too thick cups I never used CCI again. YMMV