Well harrumphhhh, spit......
I just got done writing about half a book and it evaporated into the ether.......
OK, condensed version:
You are building a perfectly fitting for your rifle chamber cartridge; you can do this because, unlike the factory, your loads are for your gun, not every like chambered gun out there. Your 45ACP loads are for a nicely designed and executed auto-loader chamber which is usually to a higher standard than a lot of rifle barrels. Your process is good for your pistol, your rifle is not your pistol.
Forget about orienting the brass with a mark on the base, at least for now. Unless you use the advanced technique of reading the interior of the case wall thicknesses, 360deg. from base to mouth, to orient the case interior body proper (that is where the shaped charge is coming from) it will do no good. It wont do you any harm, either, just wont do what you thought it would.
Are those once fired cases from your gun? if not make sure they all chamber up in yours then do the case mouth prep. to be able to introduce the cast bullet base.
Use 10.0-12.0 of unique to get used to the gun. My guess is the .459's over the Unique will do well right off. This is where a dummy may do you some good. If a case that fits the chamber well doesnt fit so well with a .459, the .458 may be just what you need. You really need to pop off a few in your rifle (twice will completely do it) to get real, fully fire-formed to your chamber cases. So make some that fit (5 or 6) and use those for initial developement.
Yes, its that easy, when your cases fit your chamber, to decap (I use the Lee Universal Decapping Die), recap, powder and 'ball'. When you are not making HOT loads (and typically, almost by definition, cast bullet loads are not hot) you dont need to resize unless the cases get sticky to chamber up or extract from too much expansion (or you get a 'new' lot of once fired from another rifle and want to start from the beginning with them).
Seat to depth; ie, the crimp groove and use only about as must crimp as needed to roll that little bit of flare back around the bullet and maybe a smidge more.
FLS a couple sticks of the once fired, same headstamp brass with each dieset. You may find that the size die/expander ball in them gives slightly different bullet to case fit.
IME, if the bullet fits the expanded case neck to fill the chamber throat well, it doesnt seem to matter if my bullets are soft lead or the harder WWts they dont lead up at BP equiv. velo's. with smokeless powder. I dont water quench or use Lino and even 'hard lead' is pretty soft compared to jacketed bullets, so FIT to the THROAT is CRITICAL.
