I am about to assemble my first efforts for a 45-90. I will first be going with a Gov. 405 grain pill and initially play with powder amounts and seating depth. I have a yet to be used lubesizer. The question: If one is not going to seat all bullet grooves inside the case, should the exposed grooves still contain lube? Any starting load suggestions would also be appreciated. Sorry to be a bother, but it's a totally new realm for me and seems a bit more intricate than bottleneck smokeless stuff. So little time....1Minute

If you're not going to be carrying those cartridges for hunting or such then lubing all the grooves is a pretty good idea, the more lube the better. But if you were carrying those in a cartridge belt or such that the exposed lube would collect dirt while hunting then leave them unlubed.
Good place to start with a load would be fill the case with powder until you get enough that with the bullet and wad fully seated they just sit firmly on the powder. Shoot a few and then go up until you hit the sweet spot.
A couple of things you'll find vastly different from smokeless. Bullets touching the lands may not be worth a poop for accuracy.
Powder charges can vary as much as a grain and nobody will ever know the difference.
Crimp is not our friend with bp loads.
Bullet size is way more critical with bp loads than smokeless, bp doesn't bump a bullet as much as smokeless so if it don't fit tight to start with it'll leak alot of powder gas past and make for some nasty barrel fouling and not so good accuracy. .002 over groove diameter is usually a pretty good place to head for.

Ranch13: Thanks for the response. I made the mistake of doing too much reading before I got started. That being, I was becoming overly concerned about slugging the barrel/chamber, ordering custom molds, and brass tuning etc. Think I'll just get out and blow some smoke to start with, and do the science stuff later. Take care, 1Minute

1minute about the only number that means a heck of alot is the groove diameter of your barrel. Then you want your bullets .002 bigger.
Beyond that just loading up a bunch, and make em go bang for the heck of it is a dang good place to start . Have fun.

1minute,

Before you go much farther, I'd suggest getting "The Black Powder Cartridge Primer" by Steve Garbe and Mike Venturino. This one book has everything you need to get started loading for BPCR. It doesn't have ALL the tricks and shortcuts, but has all the info needed to get you started on the right track. As you gain experience and familiarity, you will make adjustments as needed on your own. Or come back here and ask more questions . . .