Think of it in terms of the 300PRC. A chamber designed with long for caliber bullets primarily. The 300 PRC doesn't smoke the 300 Win Mag on a spread sheet. They actually look pretty similar, but the PRC is a SAAMI chamber with the longest, heaviest bullets. I don't look at it just in terms of velocity. If that were the only motive we could stop long ago at the 7STW, 7-300's, 7 WBY, 7RUM and an exhausting list of other 7's including the Nosler, it was designed to create a 162 gn bolt of lightning... but you can't shove a 180 or 195 in that without creating a bunch of problems. My hope for the 7 PRC was that it would be all of that and and still be SAAMI, for all of the reasons like fitting in the chamber, safely, fitting in the magazine, freely and so on.
The LRM gets noted often when discussing the 7PRC-to-be. It's probably the closest comparable chambering. I like the LRM but for brass. If Hornady took the LRM to market like they did the Creedmoor and PRC's, then I'd be super satisfied. They'd tweek the fitment and in no time, gun manufacturers would make it available, ADG and Lapua and the like would have head-stamped, quality brass and we could all go on to debate the next topic.
So... Since the 7PRC isn't...yet... what next?