Speer Caution on 243 cases seems weird

roknHS · Jun 26, 2013

I've been using the Speer edition 13 manual, just got the edition 14 manual. I want to load some 243 shells so, I read the opening comments and was surprised to see the caution on using any brass case but Winchester. Now, I live close to Lewiston, Idaho and have a good friend that works at the Speer manufacturing plant (ATK). I asked him what 243 cases they make. He said they make 243 brass for most major brands and it's all the same.........they just stamp the base with the brand they are making that day..........it might be Winchester or Federal or whatever. The cases are all the same.
According to the Speer caution, excessive pressures can result with any brass case except Winchester. Even if I had cases from some other manufacturer, how could the brass case affect the pressure to a point where a Remington or Federal case would be dangerous and a Winchester case would be safe (all loaded exactly the same)?
Am I missing something here? The edition 13 manual has no such caution........granted edition 14 does increase some loads by a couple grains of powder. For the most part, edition 13 and 14 are close.

I e-mailed Speer and asked them to give me more information on the caution.........they just repeated what the book said..........nothing more.

I hope some of you with more experience can shed some light on this for me.

deadshot2 · Jun 26, 2013

roknHS said:
Even if I had cases from some other manufacturer, how could the brass case affect the pressure to a point where a Remington or Federal case would be dangerous and a Winchester case would be safe (all loaded exactly the same)?

Brass can vary by volume from manufacturer to manufacturer. It's very possible that your friend may be unaware of a change made "upstream" from where he works and has knowledge of. Thicker walls for cases are the most often cause of higher pressure.