Well I've been talking to a few people, and doing some more research. I've decided to go a completely different route. It looks like I'm going to change bullets, and go with the 95 gr Nosler Partition. I'm also going to break down and get some new powders. Off to Sportsmans this weekend hopefully.
I have learned a lesson from this though. If you're not finding a lot of information with a particular bullet and powder combination, it's probably for a good reason. Haha. I loaded some more of the 85 gr HPBT's yesterday evening, and played with seating depths. I snuck off early this morning to the range before work. I didn't have as fancy of a target this time, but it didn't really matter. They shot like crap again. For good measure, I also brought some known good loads with me (the ones in my sig). The 55gr Noslers shot a 1/2" group on a hot barrel. So it's not the gun, and it's not the loose screw behind the trigger. My gun just doesn't like that combination. I'm sure with enough time I could find a decent load for it, but from what I saw, it was going to be a slow round (sub 2900 fps). Roninflag has pointed me in the direction of a "known to work" combination, and I'm going to try it. Thanks again for all the pointers and information. I'll be sure to update this once I get some powder and bullets.