spinafish, you don't specify what the game/target is so although I'm guessing white tailed deer giving advice on specific bullets is kind of tough.
In any case, I would suggest contacting the manufacturers concerned and asking what minimum threshold velocity will guarantee achieving the full intended functioning.
Hornady is perhaps the best manufacturer to start looking at in that they publish (on their site) the velocity ranges in which their bullets are intended to function. I do enough work on and writing about reduced loads to wish that everyone did so.
Please understand that I'm only expressing my own opinions but...
Testing on wet phone books, sandbags or water jugs will only help if you are hunting wet phone books, sandbags and water jugs. Living flesh offers very different challenges to a bullet. Animals don't feel or react to trauma like phone books, sandbags or water jugs nor do bullets shot into those targets perform the same as when shot into the flesh and bone they are designed for. "Testing" hunting bullets in such targets has roughly the same applicability and level of resulting confidence as testing a tree felling axe on a steel tree.
It is not what the axe was designed to cut.
H4895 can be loaded down to 60% of the maximum powder charge for any load listed for that powder. That's a lot lower percentage of the maximum charge than the loads listed in the Hodgdon page for H4895 reduced loads. You may find that a heavier bullet at an even lower velocity is what you want but the best way to find out is by contacting the bullet manufacturers.
As already expressed, light for caliber bullets are often varmint bullets and a quick check with the maker can help weed those out since they often are lumped into a big game bullet line. The bullets listed on the Hodgdon reduced load page are all proven deer killers, in the stated reduced loads, to 200 yards.
Hodgdon has a wealth of data that is not on their site. If you call them they can likely either provide you data or tell you how to compute the most likely velocity range a reduction of XX% in charge will net. My personal experience with H4895 is that the drop is pretty linear but they can confirm or deny that for you.
Once you can establish the baseline velocities need for the available bullets you can develop a load that will have a reasonable chance of doing all the things you want it to do.
You have more than a half year to come up with a a hunting load. Santa only needs to provide a load that goes "Bang!", makes a hole in a target etc.
For now I'd suggest concentrating on low end loads for practice. You've got a lot of time to brew up a killer reduced load for next season.
Good luck and please allow me to say that I envy you the company of the lad. We raised 6 kids on our farm, 5 boys, and the smallest is now 6'1". I miss having younger ones around.
Lance
Edit: here's the link to Hornady where they list the recommended velocity ranges for most of their bullets.
http://www.hornady.com/bulletsAnother good choice might be the 85 grain Barnes TSX BT. A reduced load of something like 31.5 grains of H4895 would net a velocity (22" barrel) of around 2,550 FPS. That is more than fast enough and hard hitting enough to guarantee functioning and enough penetration for deer to 200+ yards. It will also keep the bullet within 3" above or below the crosshairs to about 250 yards. That seems to be pretty good for a "reduced" load.
If you were limiting shots to much closer ranges you could pull even more steam off the load.
