Its namesake was rocky gibbs, he developed 7 or 8 cartridges from 24 to 338 all based on a 06 case improved to the absolute max.
its a 30/06 with the shoulder pushed forward far enough that it has one caliber of neck length and sharpened to 35 degrees, this one was reamed to 270 win length so it'll have a longer neck.
a lapua 139 scenar(bc .615) at 3300 fps has the same trajectory to within 1/2 MOA of my 7mm AM 160 accubond at 3500 fps. to 800 yds.
James, i'm gonna do what you're doing.i've got a 6wssm that i'm gonna get working so i can use it for practice over the summer.i think the ballistics will be somewhat in the same ballpark as my 338/300 so practicing with it this summer will be somewhat educational and save the round count for the big game rig this fall.