I have a Pedersoli M1861 rifle-musket that I plan to shoot with .575" conical bullets; got both from Dixie Gun Works. The bullets have no lube on them. Should I shoot them in that condition or should I grease the grooves first? Would probably use Bore Butter.

Get some books on shooting rifle muskets and read them before you do anything. Hell, just look on the internet; probably 25 percent of what you read might be valid.
Yes, you need to lube the bullets with some sort of soft lube; crisco works well. It is not just to lube the bullet, it is to keep fouling soft. Bore butter is the expensive option. Some will say to fill the cavity with lube; I don't. Might try it.
You will like shooting it. Use real black powder, 2 fg. 60 grains, or so. 60 was the original load. None of that modern stuff.
Clean with water, which is the original solvent specified for it.

Ok thanks, have plenty of Crisco. This is not my first muzzle loader, but I have always bought pre-lubed bullets before so had to ask.

Good advice, Sputster.
Three things about getting "Minie" muskets to shoot well:
1. Matching conical diameter with land diameter.
2. Choosing a design with the skirt portion of the Minie being of a compatible thickness with the charge you plan to use (and ensuring the lead is dead soft or close to it).
3. Using enough and the right kind of lube.
A friend in Australia who shoots Enfields in competition to 600 yards lubes the rings with a mixture of sheep tallow and beeswax, and he packs the base with candle wax sealed with a card wad. This latter tends to act as a plug, like the original rounds which came with wooden, clay or even metal plugs that would be driven into the base ensuring the skirt firmly grips the rifling.
There's a lot of science to getting these muskets to perform fully to their capabilities, so don't be afraid to experiment.
Hope you will post your results.

Thanks Bill, good notes there.

I took the M1861 out a couple of times and got some initial shooting done with it. To start with am using the 480gr Dixie Gun Works lead .575" minie balls over 60gr of Pyrodex RS, with RWS musket caps for ignition. I lubed the grooves with Crisco, but did not fill the base.

My first time out was just a few shots from the standing position, and made reasonable hits on a silhouette at 50 and 100 yd.

I took it out again, shooting from a rest to establish more of a baseline. At 50 yards it hits about 1" high and 2" left of POA, and at 100 yards it is about 7" high. These are all using the 'battle' sight with the 3 and 5 flipups laid down.

Shooting at 200 yards proved a little more of a challenge, as I had expected. With the 'battle' notch, I could not place any rounds on a torso sized silhouette. I then remembered some research I did on the internet, and raised the '3' flipup and aimed at the base of the 200 yard target. I was rewarded with mostly center hits, and when I shot at a 24" steel plate also at 200 yards, I achieved consistent hits as well. This looks to be interesting.

Sounds like you are on the right path, Sputser, if you are making hits at 200. One thought -- you will find real black powder less corrosive than Pyrodex, and 777 both more powerful and with very little fouling.

I know that Cabela's carries both Pyrodex and 777; will look at the 777 as well. Am not sure where to get real black powder but they must have some somewhere in KC.