Chuck Hill (Big6x6) shot some of those same bullets out of one of his Whites. Think he found the sweet spot. Here is a copy of what he posted:

"Wednesday I had to go to the range to sight in Terrells Disc Elite for the hog hunt..No Problem! I took along the White 97 .45 just to pop off a few shots. I fouled the bore as normal and then shot three, 3-shot groups at 100yds. Load was 80gr by volume fffg Triple Se7en and the 420gr Bullshop .451 conical. You can tell which group was which because I was moving the w/e adjustment from high at 100yds to dead on at 100yds just in case someone wants to pop a hog with it at close range. First groups was lower right, then lower left, then center. Group sizes in that order is 0.97, 0.99, and 0.63! If I'm not mistaken, that is the three smallest, most uniform groups I've shot in that rifle! I've shot single groups that were smaller, but never any three that were that consistant. Average velocity was 1387fps."