smlemon,
Not sure where you got your information, but pretty much all of it is incorrect. As already stated the Alaskan you're refering to was most definitely "never" used. Although some coyotes trying to sell thier wares on ebay try to claim so. Also the zeroing process is done at 100 yds. If you're chasing an A4 or building an A4gery, you really should read these, specially the second one, pages 13 thru 25. Good stuff to know, will probably even save you some money.
http://www.90thidpg.us/Reference/Man...3_AT_A3_A4.pdf
http://www.90thidpg.us/Reference/Manuals/TM%209-270.pdf
On another note, adding to chucks comments on the current garbage Redfield base, a very large quantity of them wouldn't even fit the rifle correctly. When you tried to screw them down they sat on the action at an angle,,, sideways. I (and several others) contacted Redfield about it a few years ago but never saw any sort of response, like chuck, it's been about 4 years since I got one and I gladly got rid of the last one. Maybe now they have it fixed, dunno?