Dave –
If you have a .44 in a handgun – or plan to - and start reloading, I strongly recommend you never build loads that won’t work in both your rifle and handgun. Any ammo you buy commercially should be OK in either, with the possible exception of feeding problems from a magazine – don’t know about that and it probably depends on the rifle.
As to your original question, “killing range on a white-tail with a 44 Mag. rifle, much will depend on the load.
Here’s some info for my 240g load from my Browing B92 (20” bbl):
Load Data
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Name: .44 Cal, Speer JSP, 240 grn
Ballistic Coeff: 0.164
Bullet Weight: 240
Velocity: 1880
Target Distance: 145
Scope Height: 1.500
Temperature: 70
Altitude: 500
Ballistic Data
~~~~~~~~~~~~~~~
Range Elevation Velocity Energy
0 yds -1.50 in 1880 fps 1883 fpe
25 yds 0.71 in 1774 fps 1678 fpe
50 yds 2.21 in 1674 fps 1493 fpe
75 yds 2.95 in 1577 fps 1325 fpe
100 yds 2.83 in 1485 fps 1175 fpe
125 yds 1.71 in 1400 fps 1044 fpe
150 yds -0.55 in 1321 fps 931 fpe
175 yds -4.01 in 1250 fps 832 fpe
200 yds -8.90 in 1186 fps 750 fpe
The range at which I would take game is limited by my ability to use the iron sights on the Browning rather than the energy delivered. I shoot clay pigeons at 100 yards and steel gongs at 200, but wouldn’t take game beyond about 150. with a low-power scope a whitetail at 200 yards would be in serious trouble. But at that range I would MUCH prefer my .30-30…