I just started going down the rabbit hole. I've got an RPR. I'm starting her off with a diet of 285gr. ELD-M, mostly because I put up a .333 MOA group at 400 with my brother's .338 and did that with Hornady factory, so I know the bullet will shoot. I'm just too cheap to pay $4/rd. for factory ammo. I chose H1000 to start off. I taught my brother all I know about reloading between two beers, but he went the Retumbo route. He almost got under .6 MOA with his first batch of reloads. He thinks he started to save money but I set him straight. That is a lie we tell our wives. I got sub-MOA groups at the low end of the load range. And in the middle. And at the top, interspersed with groups not worth writing home about. One grain increments seated just deep enough to fit mags with an 0.080" jump. I won't be single feeding. One group SD of 5, another 152. With five shot groups. The next batch will try seating depth at a 0.020" apart. Then I'll fine tune the powder charge, find a good load and get my dope down. Then I'll need to find a place where I can really stretch it's legs. I'm currently limited to 400 yards.