devious169-
Welcome to the 450B forum. We hope you will find helpful info here, and be able to contribute helpfully from your own experience.
For your specific question about loads for the 200-geain XPB, the best starting place is the data set from Lyman. Data for the 450B with the 200-gr XPB is included in the 50th edition of the Lyman Handbook. (See illustration below.) It's tested data produced by a reputable and reliable source.
If you are using the Hornady dies and have not worked with a 4-die set previously, be sure to seek out the numerous threads about the problems associated with the set. The problems are due to Hornady's not making the effort to produce a usable instruction pamphlet for the 450B die set.
Because the 200-grain XBP is a little lighter than usual, be sure to read threads in the forum on how to crimp the bullet for best powder burn and accuracy.
Here's a thread from 2011 about the 200-grain XPB that includes a post I wrote listing some prior informative threads:
Barnes XPB 200 GrainIn addition to the links provided in Hoot's meta-link post, here are some other threads about this bullet you might find to be helpful:
Let us know how these bullets work for you.
--Bob
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image linked from midwayusa