Paper patches that are wet and thus stuck to the bullet to a greater or lesser extent never gave me the accuracy that patches applied dry do.
At least not with BPCRs.
Nor will they produce best accuracy in a BPCR if seated deep in the case. But BP is not smokeless and things that work with grey powder often fail miserably with BP. One of the reasons "modern" handloaders sometimes have trouble with BP.
Bullets seated about 1/16" in the case is borne out by the Sharps Rifle Company's instructions for loading ammo for match rifles in the 1870s. But all the Sharps PP bullets were tapered and often the bores were significantly larger than the bullets. .451" bullet vs .460-.464 groove in the barrel.
The only advantage PP has is in elimination of leading. In reality they are less accurate than "naked" cast bullets.
They will shoot very well, but they do produce the occasional flier that is not likely in "naked" bullets. They are also very labor intensive if loading 300+ rounds for a match. It adds a day or more to the ammo preparation time.
I still like PP for some uses and use them in my 45-100 when I shoot it. But patching tapered bullets is not the same as patching bullets with parallel sides. So the patch has to be angled differently on one end than the other.

Dan