To begin with, the throat in a BS barrel, isn't very important. Your throat, isn't anything like a 8.15 x 46R throat, it's more like a standard 32/40 throat. The 8.15's have very long throats and the twist rated is 14.2". Grooves are usually under .319 but, can be found, up to .323.

I have a 8.15 x 46R rifle and a 16 twist Douglas barreled 32/40. The 16 twist will stabilize a spitzer bullet, that is 1.110 long, with a .060 meplat. I found this by shortening a RL spitzer, that started out at 1.160. A flat nose, won't stabilize at that length though, more like 1.06.

With a short lead, a tappered bullet helps to keep from distorting the bullet when your seating it BUT, to much tapper will throw fliers. For a short throat, I like ~.004 tapper from the groove size, not the base band. .002 for longer throats.

Bore riding bullets, like the Hudson bullet, work well too. For that, you need a nose, at least .001 (.002 is better) larger than the bore size and .001/.002 larger on the base band than the groove size.

Also, nothing harder than 16/1 lead/tin alloy, Everyone should start with 20/1 and try experimenting with it from there.

When Frank speaks, I listen. (I'm forever in his debt for an old .30 GC'ed spitzer design of his, 309-169 FN (Elco), that is a never-fail in my Springfields.)

Anecdotally, that Accurate 185gr. Hudson bullet is my favorite go-to in a couple .32-40's, a couple of them with diameters tailored to specific needs.