DoubleA,
The 460 grain No Excuses shoot great out of my Huntsman 24" Stainless Steel barrel. Make sure you get the ones that are .503, they engrave lightly on loading. I shoot them over 70 grains of 777 FFG and average around 1-1/4" @ 100 yds. Just remember "the bullet length cannot exceed twice the diameter of the bullet", so you are basically limited to a 1.00" long bullet.
The PowerBelts also shoot good and are also legal in Colorado. 80-90 grains of 777 under a 295 grain or 348 grain should get you close. I prefer the 348 grain. Good luck.