I'd stick with the .25ACP priming system, with Fiocchi magnum small pistol primers, since you're already set up for it that way. But among 209 primers, I've had the best performance with CCI 209 Magnums. Cheddites delivered identical performance, but the sealing paint on the flame end always sticks to the o-ring inside the primer pocket of my aftermarket carrierless breech plug. CCI doesn't have that paint, and it fits the pocket tighter around the circumference. Sometimes I have to use a steel 209 capper/decapper to get it out. But the groups are totally worth it! As for cleaning the plug, I use an RCBS large pistol/rifle primer pocket cleaning brush, gently, which rips the crust right out in big chunks. I use a teensy weensy drill bit to clean the flash hole. The Montana Extreme Blackhorn solvent I use on the barrel, loosens up the crud in the fire channel to where I can get it out with a Q-tip. Good stuff. It's almost as though the soot from the little bit of BH209 powder that falls into the fire channel, actually prevents primer char from buliding up.