Ok, I've seen this a hunderd times.
1st, no joke, if you have true sperm oil don't waste it for patch lube. The oil from the head cavity of the Sperm whale is $50 per oz. round these part's, clock makers use it.
Now, onto the problem. Changing lubes for prb is not as important as the amount of any of the given lubes as applied to the patch. Spit works fine,if the gun is to be discharge immediatly and/or if the bore is not hot from repetitave firing. Think like this,"is the patch damp with spit or really slathered?" is it the same each time?""everytime?" I use spit patch fer tween shot swabs,damp.
After years of shooting traditional bp and having fun and sum success,I began experimenting with patch lube properties. I got an old eye drops bottle and found 2 drops of lube on each precut patch shot different than 3 drops per precut using 5 shot groups. I finally found that using 4 drops on three patches rolling them tween my fingers to spread the lube throughout the patch worked best,,,ya have any idea what kind of PITA that is!? Well more later,,,, my point is there are many many fine lubes on the market and some that have been used for centuries, it's about finding the right amount for your gun,powder,ball,and cloth. Think,,poor. Think,, conservative. Think,, every shot count's,how can I keep it the same?
When the group fall's apart it's not because you have failed,,your learning something,ya just have to find out what it is