"Modern" potential of 45-70, 45-90, 45-110, 45-120 + ???

[mattparliament]

Alright, I'm curious and intrigued....

Firearm limitations or integrity set aside let's talk true cartridge potential.  I have some serious curiousities.

What can we do with these "old" cartridges?  You know, the 450 Marlin can push a 250 gr. Barnes at 2400FPS ish, cool.  Most handloaders of the 45-70 know this is obtainable in the right action.  It can also do great things with 405 grainers.  From what I've read and understood the longer cartridges from the 45-70 can do better with similar or lower pressures.  Let's leave black powder out of this and keep up with the modern theme of the thread, different hobbies/interests/specuations, no offence meant to black powder enthusiasts, bottom line, that is fun stuff!!!

Let's try this, what has been done with light weight loads in the 45-70,90,110,120, and in the same breath the heavy stuff, the 405, 450, 500 and so on also intrigue me.  WHAT'S THE POTENTIAL??? Can we touch 458 Win? With the disclaimer of firearm durability left aloof...

for some comparison, a neat article about the 444 marlin was in last months G&A.  Cool thing about that is that the 444 Marlin is "similar" to the 45-70 dimensionally but has the availability of 180, 200,240 (of course) and so on for bullet availability.  Imagine the fun we'd have with a 200 grain copper bullet in the 458 caliber.

Let them roll and let's have some fun!

Matt

[Nobade]

Sure, 45-90 in a Ruger #1 will pretty much duplicate the 458 win mag. The longer ones will hold more powder, and go faster. You just have to be sure of the quality of your cases. Starline 45-90 cases will take some really high pressure, but I'm not sure about some of the longer ones that are lathe turned. But of course it's all kind of a moot point. Just use the full length magnum case, such as 458 Lott or 450 Ackley and you have all the speed you'd want. If that's not enough there's the big Weatherby case. They're made for this kind of thing. 

[OhioCruffler]

I wanted a big-bore boomer myself.  I got a .50-110 Sharps (Sharps 2.5") barrel for my T/C Encore.  I can brush 2000 fps with 500 grain bullets, and still shake the fired case out of the chamber; no pressure signs are evident.  I can't use the wood stocks; they break and I have ripped the front forearm screw out of the barrel with the recoil (I have a brake mounted).  Once I get another method of attaching the forearm I can do some better load development.
I believe I can get to .500 Nitro Express levels safely.  I already have the .500 Express beat.  I use Starline brass exclusively!

So yes, with good cases and a robust rifle these old BP rounds can really rock, but care must be taken to ensure they do not find their way into an old rifle. These loads would not be safe in a real Sharps.  For this reason, when I get a .458" bore boomer, it will be in .458 Lott.  then I don't have to worry about being responsible for taking someone else's rifle apart if my ammo finds my way to them.