Most .223 varmint rifles will thrive with 50-gr bullets. Good for every pest from cockroaches to coyotes. (Well all right, they do over penetrate on cockroaches, LOL!)
Either of Ramshot's suggested loads using TAC or XTerminator work well, as will 27.0 W748, 24.0 H322, or 25.5 A2230. You wouldn't be displeased with book loads using Benchmark, RL10X, A2015, RL-15, 3031, 4198, 4895, BLC2 or a half dozen other powders, for that matter. I do find Varget to be a wee bit too slow for bullets of that weight, though.
You got that right. 40 to 50 grain bullets, usually Vmax or Ballistic Tips, have accounted for close to 98% of the critters that I have taken with my various .224 bore guns in my life. The other 2 or 3% being taken by 52 or 53 grain bullets.
