Here's a lesson in facts. Instead of posting or believing old crap about technical information that might or might not be true, contact the manufacturer directly.
Only the manufacturer can provide the facts on their products. Don't trust some yahoo on a forum. Forums are notoriously riddled with BS. If you have a technical question about a product, ask the manufacturer.
In the case of CCI primers or products, you can use this link to ask them directly:
https://www.cci-ammunition.com/contactus
That's what customer service is for. Ask them.
Because of all the rumors on forums, I asked CCI directly if their 550 and 400 primers were the same.
They said they were not. But don't take my word for it, ask them yourself.
https://www.cci-ammunition.com/contactus
Or we can do a little research and draw some conclusions based on information.
For example, I recently began loading the .30 Carbine cartridge. Being a
rifle cartridge, I just assumed I needed to use a small
rifle primer. But then one day while I was charging a .30 Carbine case with 15 grs. of H110, it occurred to me that my .357 Magnum hunting loads use a heavier charge of the same powder, but I use a small
pistol primer in the .357. Then I remembered reading a couple of articles by Brian Pearce on loading the 32 WCF (Is it a rifle cartridge, or is it a pistol cartridge??) in
Rifle and
Handloader magazine in which he used a variety of primers. So I tried in the .30 Carbine, with the same powder charge, SR, SRM, SP and SPM primers in Fiocchi, Wolf and CCI. The bottom line is, there really wasn't enough difference in velocities to spit at, which of course means there wasn't enough difference in pressure to spit at. Certainly there were no spikes in velocity.
Think about it: Why would rifle cartridges such as the .22 Hornet, 218 Bee, 25-20, et al, use small rifle primers, and cartridges such as the .357 Magnum, which use more powder, use a pistol primer?
I'm not suggesting the use of SRP's in a .357 in the place of SPP's, but if the latter were all I had, I'd use them.
35W