I hope this is the correct place to post this...

I just received a Golden Ticket from My Bride for my LONG awaited Bison hunt...

I plan to use my Marlin XLR in 450 Marlin...

That said I have loaded up some 400g Speer Bullets to about 1900ft/sec.

Do you any of you have any experience with this bullet on this type of beast?

I shot a couple bull bison with cheapo 405 gr Remington JSP @ 1900fps (54.0 gr imr3031)and the results were pretty impressive BANG/FLOP of course I was shooting to break their necks.
Do yourself a big favor and find a skeleton picture of a bison their spine in the neck behind the ear is where you want to hit them...and it iswn't where you would think it should be, just look at a picture of how their heads are attached to the neck and you'll see what I mean.
don't waste a piece of the meat as it is excellent on bulls up to 3-4 yrs old.

Put a bullet right between their eyes. They drop like a rock, no meat wasted.
Thanks,
Tom