henry1, I have come to the conclusion from reading lots of posts on the internet about this subject that in a 45-70 for deer it doesn't really matter what bullet you use as long as you can put it where it needs to go
I have shot several deer with my Marlin 45-70 over the years, just got a handi about a month ago and have taken a deer with it also. I have used the Hornady 300 JHP, Remington 300 JHP and the Remington 405 JSP in handloads to take deer and I have taken one deer with my Handi using a Winchester 300 JHP factory load. I really like the Remington bullets, they're less costly, shoot great and do a number on deer. The Remington 300 JHP bullet shouldn't be pushed much over 2000 fps, it will still get your deer with authority but expect lots of meat damage. The last deer I shot with the 300 Rem bullet was an eight pointer and he was about 80 yards and broadside to me, I had the bullets coming out of the muzzle at 2250 fps. I hit the buck right behind the shoulder and he went down instantly. I walked to the buck and rolled him over and I swear you could have stuck your head in the exit hole.
I shot several deer with this bullet loaded to 2000 fps and really liked the way it performed at that velocity. I have switched the Marlin over to the 405's at 1750 fps, this bullet gives alot less meat damage, shoots great and is the best deal going in a heavy JSP bullet.
My Handi is going to be my 300 grain gun and the Marlin will be the 405 grainer.
I have read of several people have great success with cast bullet loads from their 45-70 rifles. Just pick a bullet designed for the 45-70, work up an accurate load and go get your deer.
All of the deer I have taken with my 45-70's (about 10-12) have been 100 yards or less.
GOOD SHOOTING!
Slufoot