Keith, not interested in spewing venom but have a couple thoughts.
First, my rifle most assuredly doesn't have a long throat. The COL for the 75 A-Max to touch is 2.464". For the 50 V-Max, 2.313". I hope you know that difference is from the ogives. How does that compare to the COL's you like to run?
Second, I'm happy to plug in any velocity you want for your 50 grain load. But to compare apples to apples we need an equivalent velocity for the 75 A-Max. That is what I did, used velocities worked up to what appear to be similar pressures in a rifle I own. It is a 22 1/2" 8 twist. For what it's worth, that little #1 contour rifle averages about 0.4" with the 50 V-Max, and better than that with the 75 A-Max.
To compare to your 3800 fps load, we need "what?" for a speed in the 75. 3250? Work up the load and we can compare.
