What kind of ballistic increase can I get reloading the .44 Magnum to perform optimally out of the 16" tube of a Winchester 94 Trapper Carbine?

How fast could I safely push a 300 grain slug? How strong is the action in this rifle?

Thanks for your responses.

Although not using 300 grain bullets (I use 240 grain) but using the same loadings I get 1692 fps out of a 7-1/2" barrel and 1919 fps out of an 18" barrel.

I know this doesn't answer your specific question, but it may be a guideline for you.

I have a Ruger 96/44 and I get 1565 fps from a 18.5" using 310gr. WFN/GC bullets over 20.5 gr. of H110.