To further support Daryl's comment on bore obstruction etc --

With a proper powder load you won't be seeing stuck wads (with brass case and no base wad).
I'm seeing my wads (from the cartridges seen above here) on the ground about 75 yards down range from the muzzles.
I'd expect patched roundball to drop them a fair bit closer to the muzzles, but again with a proper powder charge you won't stick your wad column.

Cheers
Tinke