Thank's all.
Sorry for the late reply, as work had me taxed for time on the net.

NE450no.2---right now the only .450 I have is a simple, but sturdy Ruger no.1 that's been re-chambered---guess it's your basic do-it-yourself Nitro.
Shoots pretty good though.
The double Rigby .450 I "had" is now in my nephew's safe, and is not being fired anymore. I do not have a safe, and have had a hard time finding hiding places. Unless I dig a hole in the ground in the back yard.
But, I'm getting a safe pretty soon, so it may be returning home soon, although I will not be firing it anymore. I've pretty much returned to basics with my rifles now, and am going to be carrying things like this Ruger. It's basic, it duplicates the ballistics easy, and I won't mind if it gets scratched, because the last barb-wire fence I went through with the double almost gave me a heart failure.
I figure I can do anything with the Lott that can be done with the .450 and more. It's got two more rounds ready to go in a pinch.
But I'm still gonna hold two more twixt my fingers, because of habit.
I've been reading through some post's on Accurate Reloading, and figure with the RL-15, about 84 grns. with the 500 Woodleighs.
Actually, I don't NEED that much-as 80 grns should put me at about 2150fps, and that's all I really wanted to do, was duplicate the velocity of the .450 and .470
I'm not much into all of the hype about higher velocity. I've seen the originals at work, and that's all that is needed.
Time tested, so to speak.

Got it figured out I think, but I'll post a pic of that rifle when it gets here.
Labor Day, and the weekend holdover, put a hold on it getting here, and I'm about to climb the walls as it is, with anxiety.
But anyway. I'll make it.