With as large a flame front as the sixteen bore will have I wonder about leading when shooting without wadding.

Looking at British proof loads from the time this gun was made, it seems as if the proof load was 75 grains of powder. I'll have to look again to see just what powder they were using, but I think the documents I was looking at stated 75 grains for ball or shot at an ounce of either at sixteen bore.
That would make sense with the powder measure this gun came with will throw 75 grains at the setting that I found it at and with the cork plug in the base of the measure.

I'm also interested to hear about what the typical practice is in respect to bullet jump.
Should this gun be loaded with the ball touching the rifling or with a little set back to allow for a bit of jump?
I have the sense that with black powder, it'd be best to have the ball touch the rifling.
With the paper cases, it couldn't be set up to engrave the rifling, the paper just won't hold tight enough.
I've seen crimped brass bore rifle cartriges loaded with ball, I'm sure that makes them much easier to care for in storage and in the field, but it seems it'd be a bit of a task to set up crimped cases for ball that would engrave in a nine groove rifle.

As I'll be building metallic cartriges, and will likely stick to ball loads unless I hear of a good conical for this system, I can set up to load ball in a light friction fit and still touch the rifling, given that I taper the outside of the cases at the chamber throat end of things.

I don't have a website to post photos on, so if I do photograph what I have here, I'd just have to send them to you if you wanted to see what's going on here.


so.

Is lead buildup a problem when shooting without wads? Do I engrave the rifling, just touch it, or set up for a little bit of bullet jump?
What's the best way to go for this big of a bore and charge of black powder?