I use RCBS and they work good. My only problem was trying to load the Hornady Flex tips. They were too long to work in the action of my 1895 guide gun.
Bummer about the flex tips.
This is the kind of information I need.
Maybe I should rethink my bullet choices?
I am learning all of this, as I have no direct experience other than commercial ammo.
I guess I used cowboy commercial loads in the past for both rifles.
I would google about reloading the 45-70 flex tips. I trimmed some of my brass so I could reload the flex tips but I trimmed the brass to short and could not crimp the brass. There might be a length to trim so they work but I don’t shoot that rifle enough to worry about it...so I bought factory flex tips.
Seems to me I remember something about Hornady brass being significantly shorter when they come from the factory with the FTX bullet. I have yet to load for mine but I keep that in mind when sorting brass. Unfortunately I don't shoot the rifle enough to worry about loading for it at the moment.
For the price and availability, you cannot beat the Lee dies. I use them and many more expensive brands. But, for the good ole 45-70, I like the Lee with factory crimp.
If there's an RCBS cowboy set for it, I'd go that way. My understanding is those use a stepped expander like a Lyman "M" die for "belling" the case mouth. It's not a necessity, but a nice thing to have.
Flex tips require you to trim your brass to a length that only works for them, so they'll cycle in lever actions. The Hornady manual states the specific trim length for them. That's their big drawback for reloaders.