I agree with hunter5325. I too have found those Nosler velocities to be "optimistic" quite optimistic, in fact, in a number of rifles of different calibers.
Your velocity problem is not caused by the way you are seating the bullets or crimping/not crimping! More likely, by a too-light powder charge.
In my 7mm Rem. Mag., a Ruger No. 1 with 26" barrel, it takes 71.5 grains of H4831 to get 3350 FPS with 140-grain bullets, and 70 grains of IMR 7828 to get 3050 with 175-grain bullets. I get 3000 FPS with 140 grain bullets from a 7X57mm caliber No. 1A Ruger with 22" barrel using 53.5 grains of WW 760 or H414.
I believe it would take between 69 and 70 grains of RE22 to get the 3240 FPS you are looking for with those bullets in your rifle. But your 7 Mag. should be capable of that velocity level with 140-grain bullets without straining the brass or the rifle.
If you try it, work up in 0.5-grain increments, chronographing each batch of rounds loaded with half a grain more powder. Obviously, you must be watchful for indications of too-high pressure as you work up...... But to me there isn't much point in dragging a 7 Mag. up the mountain if it is producing 7mm Mauser ballistics!
Here's a 3-shot, 100-yard group from my little Ruger 1A 7X57mm withNosler 140-grain Partition bullets at 3000 FPS using 53.5 grains of WW 760, WW cases, Fed. 210 primers.