Cup thickness of primers

[futuretrades]

I have a question for some here dealing with cup thickness of primers. For my small rifle reloading, I have always used Winchester small rifle primers, which I understand has a cup thickness of approximatly .005 in. less than the Remington 7 1/2 primers. My question being posed here, do you think that the RSR primers will tolerate more pressure than a load with WSR primers. My thinking is, that because of the differences, in the cup thickness, between these two primers, the RSR should tolerate a powder load, of say .2 to .4 grain higher than the WSR primer will? I have been told, by someone not on this forum, that my reasoning is all wet! Just a curiosity in my little pea brain.
For the record, I have never had a problem with WSR primers in the past.

[Rick in Oregon]

Kevin: In theory, you're absolutely correct, although in actual handloading practice, my opinion would be that the pressure tolerance differential would be quite small considering we're dealing with pressures in excess of 55,000 psi to start with. A thicker cup may tolerate slightly higher pressure, but not that much. How much exactly is anyone's guess.

But I have found that the 7.5 primer will indeed tolerate a bit more pressure than the WSR or it's ilk. Here's an article and primer cup thickness chart that you may find helpful:

http://www.jamescalhoon.com/primers_and_pressure.php

We're all aware of the major difference between the Rem 6.5 and the Rem 7.5.....BIG difference that some find out the unfortunate way. I keep a good stash of both on hand, and you can bet I really check that box label prior to priming my cases.

Be safe, keep all those digits attached, and we'll see you in the rat patch in a few months.

[Jim White]

I've seen this chart many times and in addition to cup thickness, it also pays to take note of the primer height & width.

HTH

[tinytree]

like you, i have always used winchester primers for small rifle applications. they have proven time and time again to print the smallest groups in some cartridges, and i don't reckon i have ever had one fail to go bang. i use them exclusively in 223. SO! when i got the 204 i didn't even give any thought to any other primer. my very first batch of test subjects were absolutely smashing the primers, even in very mild load ranges. i hit up the forums and net info, and kept hearing thin primer cup/thick primer cup, etc., and decided to try the rem 7 1/2. ...primer smashing cured instantly! and again like you, after that i started to take flak on the standard reloading forums!

to avoid being attacked, i have pretty much just quit talking about it on forums, but in my direct personal experience, the remington 7 1/2s do not show pressure signs anywhere near as much as the winchesters, in my guns. i guess i will leave it at that.

good luck to you!

disclaimer: i am not a professional engineer, cartridge designer, reloader, shooter, or foot doctor! i don't know what the various primer cups are made of, or what their dimensions are! i just squeeze 'em in, pull the trigger, and look at them.

[RAMOS]

Well, tinytree, you lost a lot of credibility when you admitted that you are not a licensed foot doctor!!!

[tinytree]

ha! i hear you! i have bumbled into how to keep my 204s from mashing primers, now i have to try to find a remedy for my aching feet!