Trying to find Bullseye plinking load data for a "light for caliber bullet", in a 44 Magnum case, I'd suggest you look to 44 Special data & then adjust that up by +6.9% (the amount larger than a 44 Special case) as a starting point. I'm assuming you want a very light power load.
Lyman Cast Bullet Handbook 4th Edition list a 205gr cast lead SWC (non-gas checked) in the 44 Special section using Bullseye. Starting is 5.1gr @ 820fps & 10.1K cup, and a max. of 5.8gr @ 899fps & 12.7K cup. The 5.8gr scaled up to a 44 Mag case would be 6.2grs.
For the same bullet using 2400 powder, 14.5gr is max @ 905fps & 14K cup. Scaled you for a 44 Mag case that'd be 15.5gr/2400, a very light load for this powder in this case.
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