I would think that you could use small pistol primers if you do not push the pressure any higher than a 22 Hornet. You will more than likely get a lot of streaking down the sides of the case. A 221 case is thicker than a 22 hornet and takes more pressure to push out the case walls. To get 3000 fps with a 45 grain bullet will most likely exceed 22 hornet pressures and pierce small pistol primers. I have 3 221 Fireballs and I think they are much better than a 22 Hornet. You can get better accuracy, higher velocity with not much more powder. I use some where in the 12- 13 grain range for 22 Hornet and about 16- 18 for the 221 fireball, depending on the powder used. BTW I use Remington 7 1/2 primers for the most part. My second choice is CCI BR4. they do about as well as the Remington, but the Remington are cheaper. Good Luck and Good Shooting