WOW...interesting post! Unless I missed it, no one replied with first hand evidence or experience regarding "low" velocity cast bullets on deer. If I may contribute my 2¢...
Several years ago when my oldest daughter decided she'd like to hunt deer with me, I decided to let her use my FR-8 Mauser Scout Rifle. I chose this rifle because it's short, light and I find the forward mounted scope is easier to use for people who aren't familiar with scopes. But as we all know, physics dictate that lighter rifles kick harder. So I decided to go the cast bullet route and develop a load using a 311291 HP. Cast from ACWW it weighs about 175 grs. Long story short, I settled on 22 grs. which netted around 1850 fps. Not a barn-burner, but would group 5 shots into less than 1.5" @ 100 yds. over and over. She wound killing her first three deer with this load and rifle. We eat lots of venison and now, when I want a "meat" deer and know my shot will be 100 yds. or less, I almost always use this rig.
With said load and rifle, this what happened:
110 yds.
35 yds.
80 yds.
30 yds.
65 yds.
45 yds.
There probably are more over the years that I just didn't bother to photograph. The bullet
always exits with the exception of the doe that was shot @ 110 yds. It got dark on me so I couldn't see to recover the bullet and by the next morning, the coyotes had scattered the remains. Bullet expansion is dicey...but it seems to expand most of the time.
My theory on this subject is a hole through the lungs is a hole through the lungs and believe me, deer don't live long with holes in their lungs regardless of how slow or small in caliber the bullet was. Personally, if I was comfortable with my ability to hit with a the load described in the original post, then I'd use it.
35W