Black powder cartridge .....?

[the Black Spot]

Trying to figure some stuff out.
44 Russian load was 246 gr bullet with 23 gr of bp for 750 fps.
The 44 special with same bullet and 26 gr of bp ran 770 fps.
Why is it a 44 mag case loaded with 255 gr bullet over 25 gr of 3f wont reach 750 fps?
I think i know but i want to hear from others
Thanks

 

[LivewireBlanco]

The 44 Mag case is larger than a 44 Special so using the same amount of powder or less in the Mag will have less pressure. Also, using a heavier bullet will slow it down as well.