Rob,
Sometimes when the breech plug is not snug up against the rifling there will be some threads between the head of the plug and the start of the rifling, I had a rifle that was bad about "grabbing patches" and this was the case. If possible be sure to use a long loading rod, not practical in the field, that will give you more to grasp on to. A shooting friend, you holding the rifle and him holding the ram rod, is useful also.
Good Luck
Clint