Thanks Lerch.
About the 1500 yard club, let me first wish you good luck. I believe that the 243 AI with a 107 Sierra or a bullet with a similiar bc will probably kill a p-dog at 1500. The question is will it die before it makes it to it's hole. As you know, no body=no pic=no entry. You will probably have to strike the upper torso to do it, which means you are aiming at an area approximately 3"x3" at 1500+ yards. That is very tiny!!
I haven't run the drop chart for your load, but I can tell you that a 107 Sierra at 3350 barely poked a big enough hole in Brian's 1500 yard chuck to kill it. If the chuck hadn't been 35 yards from it's hole when hit, the chuck would have made it to it's hole. P-dogs are thankfully much easier to kill than a 14 pound chuck like B's.
One other thing I might point out is that the 500 yards between 500 and 1000 is exponentially easier than the 500 yards between 1000 and 1500.
When I was attempting the 1500 yard club, I had well over 25 confirmed kills on chucks from 1000 to around 1350. 800 yard chucks were a chip shot, and the difficulty in the 1500 yard shot was almost discouraging. We made 6 attempts over the course of the summer before we scored!
I only tell you this so you won't get dismayed if you don't get the 1500 as easy as you got the 1k. For every 50 yards past 1k, I would say the difficulty level doubles. That is why there is almost one full page in the VHA of 1k members now and only a couple columns of guys in the 1500!
Good shooting.