I have used R-P, Hornady, and Nosler Custom. All need at least 25.4gr of benchmark if pushing a 53 gr HP to form properly. The R-P was the most resistant to forming. As for formed brass, the Nosler gives the best groups, followed very closely by the Hornady (nearly identacle). The groups from the R-P have the same exact shape as the groups fired from the other brass, but the group size is 50-75% larger. This is not by straight load transfering, but working up different loads for each brass type. My favorite of the three would be the Hornady for two reasons. It is cheaper than the Nosler, and the Nosler brass tends to come short from the factory (1.735-1.740 range), and it does not get any longer when you form it. To add to it, though this is normally a good thing, the Nosler resists growth the most of the three by far, but this is bad for me as the brass is already short. Lastly, the Nosler tends to have primer pockets that just are not very tight from the start. Or that just could be me....Thought I have not fed it through the AI yet, I would suspect FC cases to be better than R-P, as I have better luck with them in the standard chamber. I am really not trying to knock R-P cases, as I think they are kind of the standard to measure others by, but if you are the standard some will be better and some will be worse.

1. Hornady
2. Nosler Custom
3. R-P