On my custom 30-338 I am using a Huskemaw
5-20 X 50 LR w/30mm tube. Turret is made by the folks at The Best Of The West in Cody, WY where I purchased the scope. It is calibrated for the area and conditions you plan to hunt in. Mine is set up for 6000 ft elevation for hunting Idaho this Fall. If you want to hunt another area, the folks at BOTW will take your current load data and make you another turret for the elevation/area you are planning to hunt. If you put it on another rifle with different caliber, you send the data in for that particular rifle/caliber combination and the area you plan to hunt and they make you a different turret for that particular set up. Unless you want to keep buying more of these scope for your different rifles, I would just obtain data for each rifle/caliber and buy the turret for that particular situation. That's what I plan to do with my 7mm Rem Mag. One scope, several turrets. At least for the time being. Scope runs just over $1100 and the first turret is free. Cost for additional turrets is listed in their on-line store. Depending on my financial situation in a year or two, I will probably buy another one.
I tested mine here in Virginia on several ranges, different elevations. Even though the air is a bit thicker here in VA (350 to 900 ft above sea level) as compared to Idaho (5 to 6 thousand), the adjustments for each range was dead on out to 500 yards (my longest yardage distance available). For the 500 yard range I simply added an additional 25 yard click to compensate for te air density, and the shot fell right where it was supposed to. Actually, if I would have left it at 500 instead of 525, the shot would still have been well inside the kill zone.
Windage stadia are built right into the optics and the turret gives you the windage adjustment for the distances you shoot . Example: 800 yard shot with a full value crosswind means I have to add 4 minutes of wndage. Shows that right on the turret. 20 mph full value cross wind and the same range, simply double the windage.
Great scope. Outstanding optics and finite, dead on click adjustment. No more hold over for me unless I absolutely, positively have to take a nano-second shot. But of course, I won't let myself be pushed/rushed into taking a less than desireable shot. No fair to the game I'm hunting, to the guide, or to myself.
Anyway, hope this helps.