Underclocked,
FWIW, I'm thinking that the Hornet conversion isn't good in every gun. That some people have better luck with them than others. There must also be an inconsistancy in case to plug fit and clearance.
Yesterday a couple of friends and I decided to make a day of shooting our front end loaders here at my range. One guy has the same 209 X 45 that I have. He just got it also. so this was his first outing with it. He had read all the hype on the .22 hornet conversion and after speaking personally with Cesil, he went for the conversion and a big box of their .357 195 gr. Dead Center bullets. Which BTW, acording to Cesil, and contrary to what Randy Wakeman wrote somewhere else, aren't hand made by them, but hand inspected. The first problem he ran into is that the gun wouldn't close with the new plug and hornet case. He had to mill the hole .012 deeper. OK, not "EVERY" gun is the same but the unmodified factory breach plugs primer pocket tolerances are closer in consistancy and readily interchangable between guns.
Anyway, working up to, then using Cesils recomended loads and 777FFF. His gun was all over the paper at 25 yds. That is sand bagged friont and rear on a solid shooting table. The pettels on the sabots were all torn off on every one that was shot. Some all 4 came off, some two or three. The amount of blowback around the hornet case was incredible. It was really dirty and he decided to borrow (take & keep) :? one of my spare plugs that I was going to modify and try the winchester 209 primers that I am using. Which BTW, have ZERO blowback into the breach area. It may be due to the shape of their leading edge. His groups tightened right up. I set up an extra rod with a .45 cal brass brush to knock the crud ring out of the barrels between shots, because they really became a pain at times. Brushing between shots made a world of difference with my rifle, but not his. At 100 yds, his wouldn't hit the 4'x4' cardboard target backing. I was burning 110 g of 777FFF and shooting 275 gr Powerbelts. Which BTW group very well but I had a 4 inch flier every now and then. But then darkness came and we packed it in for the evening.
Overall, the Winchester 209's worked better and were cleaner in the breach than the Hornet conversion. The 777FFF was OK but more testing using different powders will have to happen in the near future. The 275 gr HP power belts shot better than the dead centers, out of both guns. Brushing between shots helped tremendously.
When the rains stop. Testing will continue.
Stay Safe,
Franz