For an encore with a factory 480 barrel would using cut down 45-70 brass be an issue?(I know 475/480 brass is available but I am just hypothesizing) Since 475 originally used cut down 45-70 brass I feel it shouldn't be much of an issue. The only issue I see is the slight difference in the case head size .540(475/480) vs .600 (45-70). this thread on rugerforum I found post #9 here he just turned the heads down on a lathe. That was for a 6 shot revolver though so head size would be an issue for proper fit of all 6 in the chamber. Would that even be needed for a single shot like the encore?

There is also a difference in case volume and strength.

Your chamber has a recess milled in it for the rim. If the rim is too large it will not fit within that recess.

With the broad availability of commercial brass, I see no reason to go through the trouble of cutting down brass, but that's just me.

Yep

agreed

I had an Encore in 475 Linebaugh that used the 45-70 Cutdown brass. I could also fire regular 475 Hornady brass in it also. It was a neat project. The 475 Linebaugh revolver I have,uses the cut brass also. It's not a big deal. In the begininng, I used a dremel with cutoff wheel, then final trim on my RCBS trimmer. I now have a chop saw that does a quick job.

The only problem I see is the brass, using Winchester brass it's a simple matter of sizing belling and seating the bullet. With Remington and some others, you have to inside ream the brass.

I say go for it, if that is what you want. It was a fun little project.