JBM has a list of some bullet lengths. Using that I found that the Hornady .451 230 XTP is 0.003" longer than the Sierra 240 gr JHC. Using that knowledge I figure at the Same COAL for the 2 bullets you will have pretty similar case capacity and the load data should be almost interchangeable, other than using a little caution on the max side since the Sierra is 10 grains heavier, but when you are talking 200+ grain bullets I figure a 10 grain change isn't much.

I was able to load up a bunch of 45 ACP with these 240 gr bullets and Ramshot Enforcer and had pretty good results and was very near the book velocities for the Hornady XTP's. I plan to do the same thing with my 460 Rowland at some point, but with Power Pistol and AA#7.

I'm no reloading expert so maybe I am missing something important, but I would assume that for same cartridge, same weight of bullet and same base design, but different lengths of bullet, you would get pretty close to the same performance when they are seated to the same case capacity. For example same I have 2 bullets that are both 230 grains and 1 is a flat point and 1 a hollow point. I would assume that the hollow point would be longer than the flat point. Let's say it is 0.050" longer. So I would assume that seating the flat point 0.050" deeper than the hollow point would result in the same case capacity and should be the same velocity. This is all assuming you at measuring to the tip of the bullets and not using something to measure from the ogive or some other part of the bullet.

http://www.jbmballistics.com/ballist.../lengths.shtml