Every thing Chap said is correct, but normally I do not use the same powder load; with PRB and a 1-48 or slower twist. For instance the 54 I built from scratch [1-70 twist]I load with a 535 PRB and a 1/8 inch lube soaked patch and 130 gr of RS for 2100+FPS [ 35.5 inch barrel] the iron sights were set up for the Hawaken and Mountain man matches at Friendship so they have 2 "0"s one at 100yds for normal shooting and one at 175 for long range I can hit with it where the rainbow trajectory of the 385 gr bullet with the 80 gr RS that it likes has more curve in the trajectory at 100yds than the PRB with the load I use does at 175 ydswhich makes it much easier to hit with and since I had taken both deer and bear [one well over 600 pounds] at 180 paces [we did not have lazer range finders then] with one shot bang flops I have to say a lot of people tend to overlook the actual capabilitys of the PRB. Lee