Winchester Small Pistol Primers #1-1/2
Winchester small rifle primers are great primers, but their peak pressure is nowhere near that of the CCI350. The CCI350 is a pistol primer that is “hot.”
In the different Linebaugh calibers, John Linebaugh recommends the WLP because the CCI was found to raise peak pressure by a lot in the pressure barrels he used to test his designs.
I use the WLP in the 500 S&W and the Linebaugh calibers, as well as most other calibers that call for LP primers. I’ve found that the only difference between the WLP and the CCI350 and standard rifle primers is that the “heavy calibers” lose 25 to 35fps of speed with the WLP.
I thought I needed a hotter primer when using AA1680 powder because the WLP winchester small pistol primers in the Linebaugh Max caused inconsistent ignition and stuck bullets. The AA powder tech told me that 1680 must be compressed when shot from the 500 Smith or Linebaugh calibers, which fixed the ignition problem when using WLP with 1680.
For the record, I used bullets and powder that worked well together in both the 223 and the 308, and I only changed the primer. I judged primer brissance (not brilliance, by the way) based on the average speeds it made. That may not be the most scientific way, but it makes sense from the point of view of someone who reloads. I didn’t look at the thickness of the cup, but here are the results, with the “hottest” primer on top:
I’m not sure how useful this information would be now, since winchester small pistol primers recently changed the way their SR primer cups are made. Still, at the time, I found it interesting because I was working a lot with J-words in.223.