The reason for the question is that my group size at 100 yards nearly doubled in size when I substituted CCI 300 large pistol for the Winchester western large rifle i had been using. The load is a mild cast boolit load of 14.3g of Reloder 7 and a 100g Saeco boolit in a .250 Savage mdl 16 bolt gun.
I definitely am going to try this test again. Maybe my eyes were tired as has been suggested. Maybe it's just the difference between CCI 's priming compound and Winchester 's and not a large rifle vs large pistol problem?
...Sometimes, I have a bad day at the range...you know large groups...
If there is that much of a difference and the only thing you changed is the primer, then it's got to be that there is enough difference in primers with R7 to make the difference. You could trysome of the tricks for harder to ignite powders, like a firmer crimp to build pressure, but another powder might be a more effective answer.Ian--All 30 rounds that I loaded with 14.3g of Reloder 7 and the 100g Saeco went "bang". What is the basis for your statement that Reloder 7 needs more poop than a CCI 300 gives? Do you have information that CCI 300's "have less poop" than CCI 200's?
The reason I am going through this issue is that I have 15000 or so of Large pistol primers of either CCI 300, Rem 2-1/2's or WW WLP's and only about 4000 CCI 200' or Rem 9-1/2's. These days I find myself shooting much more cast boolit rifle loads than handgun loads.
I use some LPP in some light 30-30 loads, and used quite a lot of them in various rimmed cartridges when I shot blackpowder catridge silhouette.
As for substituting CCI 300s for WLR, the WLR are/were reputedly the hottest of the LR primers. Maybe a magnum LPP would do better, thinking that they might have more brisance along with a thicker cup.