No one has made such a complaint before, so I'm going to presume that one of two factors may be the problem.
1. The gas checks may not be seating squarely. And possibley that you are using old style Lyman checks, which won't perform on my bullets unless you specify that you want to use them. Or home made aluminum checks? (I'm suspecting here that perhaps your 200 gr is plain base???)
2. The jump to rifling is a lot quicker with the short bullet, which seats deeper. But I doubt that this is real likely, as I've driven that bullet at 2000 fps from a Marlin 357, and 1600 fps from an 8 inch Dan Wesson, with excellent accuracy.
Check those checks and if they aren't real pretty both on the sides and the bottom do what it takes to fix the problem. See the other posts about gas checks to help you here.
Don't hesitate to contact me personally at the business. email LBTisAccuracy@Imbris.net. I'll do what it takes to solve your problem. The bullet should shoot under an inch at 25 yards with almost any load you dare shoot.