Lawdog,
the problem is there are several APIT rounds from different countries. 647 grain seems to be the most popular that I find on the open market, but most of it is reloaded.
I've chrony'd it out of a 29" barrel @ 2850 fps and the 647gr APIT and 660gr American Eagle have very similar impact points out to ~ 1000 yards.
American Eagle says the BC is .707 w/ .2940 fps, no barrel length specified.
YMMV as there’s no standard on the powder or fill.
Hope that helps. PM me if you have another question.
