I haven't hunted Fox or Greys in over 25yrs now, and there are none here in Utah that I've seen to hunt. However, when my dad passed away down in Texas, back in 2001, I brought his old ( I was original buyer, back in the early '80s) Marlin 783 .22 magnum rifle home. I had it cleaned real good and glass bedded around the action screw. The trigger was fine as is. I put a Simmons .22 mag 3x9 on it in 1" rings, and began playing with different rounds. I shot mostly CCI MaxiMags, both FMJ & HP and the Winchester HP for several years. Then Remington came out with the 33gr Vmax (accutip) and it was the cat's meow! On a still day, from benchrest, I have shot many .5" groups with them! I took it to WY for Prairie Dogs, and it was pure joy! ha.
In Texas we always used the Winchester or MaxiMag FMJ on everything. We shot hogs, small game in the head, back then used a Weaver 4X with fine crosshairs. I've had sevral great shooting .22 rifles; a Remington 541, TC Classic, Ruger 10/22s, 77/22mags, etc. I found that the .22 mag worked better out here in the West, and since this old Marlin shot so well, I narrowed it down to my only rimfire now. I like that Simmons 3x9 on it to, very good value for the money and accurate. I miss the small game/varmints/hogs down in Texas more than the deer hunting! lol