I can't believe Tim hasn't said something.
Do a search in this forum. You will find hours of enjoyable reading on the 45-120.
I believe the name "45-120 Nitro Express" is just a moniker coined by Jeff "jeffeosso" Smith to denote his playing around with higher pressure loads in the 45-120 Sharps. It's about as valid a cartridge name as my name for my 45-120; my 450 Sharps Express. Actually I prefer my name...
ix-nay on the shortening of the 3.25 inch case, don't know where you got that.
Based on Tim's recommendation and Tyler's experience with 405's, I just throated my rifle's chamber out a little, actually about .250 inch, so there was no question about room for 500 and 500+ grain bullets. BTW, If you need it, I sent Tyler the extension I made for the throater when I was finished with it so he could throat his rifle. He has shot 700 + gr. bullets!
And trust me, there is no need to give the rifle extra freebore to decrease pressure ala Weatherby.
I could go on and on... andonandonandon
, but you'll be happy to know I won't.
Suffice it to say there are a bunch of us here with BC's in this chambering. And like I said, go back through the topics and you will find plenty of discussion on this fun round!