As a longtime reloader,, as I read these posts,, I kept thinking; "lawyers & liability."
Loading a 45 Colt to levels above normal levels for modern handguns,, (45 Magnum) is asking for trouble. Maybe not right away,,, nor even for you. I have loaded many 45 Colt loads,, shot them in Rugers, FA's & such. All within normal loads for these guns. If I had a 460, I'd load 460 brass to the levels I enjoy,, (meaning the most accurate,, not necessarily heavy, fire breathing, loudenkickenboomers) and leave the brass in 45 Colt loaded to levels acceptable for that caliber.
This post made me cringe; "Went to the range once and a State Trooper I knew was down there shooting his old model Vaquero in .45 Colt. He couldn't figure out why he wasn't getting an accurate pattern from the gun. Found out he'd loaded 300 gr. bullets at 1200 FPS and they were all over the place."
Next,, this post screams lawyers & liability.
"The loads I did for
@BatteryOaksBilly are heavy doses of WW 296 and come in at 45000 PSI. He wanted heavy, and I think that is about as much as you do in 45 Colt cases. Loads at 45000 PSI in 45 Colt starts to work the brass hard."
Loading for other people,, if you get compensation in ANY form,, is considered manufacturing ammo by the ATF. A license is required. And if the "friend" gets killed or injured,, who's liable? Who is the family gonna sue? I know folks say; "My buddy would never sue me." But,, ask yourself; "What about the wife or kids?"
And what will you do if you were to suddenly die,, and your family takes the ammo & lets a friend,, or even your own family members use "magnum" level loads in a 45 Colt & they get injured. You'll be dead,, but you will be the reason it happened. Your surviving family members will be the ones to suffer.
This was an excellent post; "Unless you have a 45 Colt chambered gun, then I don’t think I would mess with the 45 C brass. It isn’t like you can’t recover your 460 brass, and it is easy to download the 460 for softer shooting, just use a faster burning powder. Seated in the longer brass, there will be less jump to the lands, and less carbon buildup in the cylinder to clean afterwards. Sell the 45C brass to someone that needs it."
Good advice.
Reloading should be done to improve accuracy in a gun, or to get a bullet type for a specific purpose not offered by a factory. But to reload thinking you have to max out or exceed known maximum charges or to push the limits of any mechanical object is asking for potential trouble.
Reloading for other people,, or pushing beyond the tested limits,, is asking for trouble. I have a blown up Super Blackhawk, (that I bought that way,) that I use in my Hunter Safety classes to show students that guns CAN & WILL fail if improperly loaded. I also personally witnessed a S&W J-frame get destroyed by hot 38 spl loads. Luckily,, all that happened was the frame stretched, the cylinder got the brass welded to the walls, and the gun was toast. I wish I'd bought that one to use as a demo as well.
And if injury happens,, think "Lawyers & lawsuits" and not just by the gunman,, worry more about the family.
My wife was a paralegal,, and she said lawyers file lawsuits,, on anyone & everyone they can even think might have been involved. It's called; "Sue everybody & see what sticks."
So, for the OP,,, yes,, the 460 can & will easily use the 45 Colt brass. If loading,, I'd consider loading it to more normal .45 Colt levels. And as noted above,, you will be looking at cylinder scrubbing a bit if you do a lot of it. Or,, sell it & buy more 460 brass & download it some if softer ammo is desired.
I have loaded 454 brass to 45 Colt levels,, to allow easier cleaning,, and softer shooting loads. Same with 357's. Same with 327's & 32 H&R Mags.
As a Range Safety Officer,, I PREACH,,,,,,, "Safety First!" This goes for handloading ammo as well.