Re: Help?? Target turrets.
Roy in Idaho has it right on about the objective height measurement.
As far as chronographs, I have a Crony Beta and it gives me consistent data when set up according to the directions.
I think Kenton Industries Turrets are very good. I have them on my .270 and they are spot on with my handloads out to 700 yards, at 6,000ft elev.
I have taken many many deer and antelope with them with no issues.
Leupold makes a BDC turret in their custom shop, if you send the scope in. I think most other manufacturers refer you to Kenton Knobs, or try to steer you toward BDC reticles that they offer. It depends upon what you want.