If you are using CCI small rifle why not use CCI small pistol? Any small pistol primer should be more sensitive except maybe the special Remington 5 1/2 small pistol. It is a pistol load even if you shoot it in a rifle. I use Federal small pistol in my 300 Rook.

Pistol primers are shorter thus making for a lighter strike, but I’ll experiment and share my results. 
Thank you.

Just tried a dozen Remington SR 1 1/2s. All fired! Good news!
Thank you.

Statesrights wrote on Jul 12^th, 2026 at 7:22pm:


Small Pistol and Small Rifle primers are the same size.

1Hawkeye wrote on Jul 12^th, 2026 at 9:48pm:


Small Pistol and Small Rifle primers are the same size.


I’ll say this over and over because it’s true, and this old wives tale about small pistol and rifle primers being different sizes is one of the most common BS stories in the gun world.

Statesrights wrote on Jul 12^th, 2026 at 7:59pm:

Glad that worked out.

Only thing to keep in mind is that the primers are so soft, they can cause the action to be sticky. 
If the firing pin is loose at all, the cup can flow into and around the firing pin and hole. Don’t fight it, just dry fire to push the primer back into the case.

"I don’t believe the 32-20 brass will work for the 300 rook.
Bob"


Agreed.  If it's a true Rook chamber the head on a Rook is .319-.320.  The 32-20 brass has a head dia of .350-.353 depending on make.  IT can be swaged, the primer pocket will need to be clean up afterwards.  The 32-20 has a thicker and larger rim but that can be turned.
Dabbled with this a tiny bit for a WR in my mess.  It wasn't anything spectacular so it found a new barrel and chambered it for a 32-20, shoots very well now.

Conventional wisdom on primers when I was a student at a couple of gunsmithing schools was this:

Hardest primer cups was always CCI
Softest cups was always Federal
Winchester and REM fell in between

That when building comp revolvers you could back off on mainspring weight a few oz's for Federals so these were the go-to primers for most match play

Just as important was to insure your primers were completely seated in the primer pockets so that the primer wasn't being chased/pushed by the firing pin. The trick is full seat but never crush as this will disturb the primer anvil and affect performance. It's been years since I was in these schools so perhaps cup strength has changed but I don't think much. I talk with Gunsmiths Ron Power and Hamilton Bowen occasionally and they say this is still sound advice

Rick