Yes. Primers can be hard to find. I don't load my own (yet...), and ammo for Bullseye Pistol is like the guns: Off the shelf .45 is not going to cut it.
I bought custom made ammo from someone who was in contact with the pistolsmith who built my guns. They'd talk about which powder and how many grains.
Because of the course of fire (one handed, unsupported, distance), you want as little recoil as possible, but the gun still has to cycle reliably. Yes, you can shoot a revolver (taking the cycling issue away), but almost everyone shoots a semi-automatic.
My husband was calling about primers this morning and they were $140.00 a brick.