RE: 7mm. Rem. Mag. Real life velocity???
I had some notes written in my loading manual, in the 7mag data, from last summer when I bought a 700 sps SS, 7mag 26" barrel. Load was a 160gr hot cor, over 58.5grs(max load) of imr4350, col 3.295"(on the lands) avg velocity was 2900(cronied). Got a little over 1" groups, not bad out of the box w/ the crappy x pro trigger, set at about 4.5lbs(lowest i could get it[:'(]). Recoil was not bad either.
LEE manual gives reloder 22 as giving the highest velocity for a 160 which I think is perfect for a 7mag (3075)
I also ran some winchester silver box 150s, got about 3050fps which surprised me!
As far as factory test barrels I couldnt find much on thge subject but I believe hornady use 30" barrel to test ssst slugs which is the only way you can get those things to do 2000fps I just figuerd all ammo co.s did the same.