Hi TX50cal;
I've been shooting the Hornady PA Conicals for years now. They are my favorite conical. The Maxiballs are great shooters, but I feel that the PA Conicals are better. The Maxi's are way too pricey, and I have gotten far better expansion on Whitetail deer with the PA Conical. Also, the 240 grain PA conical recoils far less.
My rifle is a 1 in 22 twist T/C White Mountain Carbine.
Actually, the Hornady PA Conical is designed to be used in a 1:66 twist "roundball" barrel. Yes, a slow twist barrel can be made to shoot a conical, as long as it is a very short bullet. The longer the bullet, the faster the twist that is needed.
My experience with the charge for the Hornady PA Conical is that my rifle shoots them well at 65 through 75 grains of Goex. I use 3F, but only because I have a short 21" barrel.
If I go above 75 grains, accuracy falls off badly. My theory is that too much charge may cause the skirt to "blow out".
Even at 70 grains, the PA conical is an awesome performer on Whitetail.
My advice would be to start around 70 grains of Goex. Probably 2F would be better...less of a pressure spike to blow out the skirt.
I doubt that you would need anywhere near the 90 grains???
Let me know what you learn, someday I may try them in a 1:48 rifle.
Oh, one other tip. For some odd reason, the first shot of the day always impacts about 2" higher at 50 yards than all subsequent shots. Hunting, the first shot of the day is all you're typically concerned with! I hold a tad low when hunting and taking that "first shot". Just be aware of this to see if this phenomenon occurs for you.
Regards,
Jerry.