I use / used CCI 250 primers in most of my magnum riles for years. However, in large capacity or long powder column cartridges (..300 Wby, 338 RUM, .375 H&H, .416 Ruger or .458 Lott) I use Fed.215 primers.
In an effort to fine tune a load in my .375, I tried the CCI 250 primer. I couldn’t tell any difference in velocity or group size.
I tried the same procedure, but in reverse with the 7mm Rem mag, .338 Win mag, going from a CCI to a Fed primer. In the 7 mag, I had to back off a grain in powder charge and group size improved marginally. Velocity was basically the same. The .338 required me to back off on the charge. Group size remained about the same, but average velocity was 23 fps less.