Crabapples: Commercial products for shooting black powder rifles work only sometimes. In your case, you have handicapped yourself right out of the gate. First off, Ox Yoke patches advertised at .015" thick are not. They are more likely around .009" or .010" thick and that is far too thin to seal your bore and prevent blowby. Blowby is when the gases that are supposed to stay behind the ball, burn the patch and get past it, fouling the bore badly and ruining accuracy. You require a Vernier's calipers to measure your patch material, so YOU know exactly how thick it is, and thus, how effective it will be. Your patch must be thick enough to form a tight seal between the bore and the ball and fill the grooves with some compression in the bottom of the grooves. A patch this thick will also carry enough lubricant to effectively dissolve all of the fouling from your previous shot as you slide it down the bore with the ball, and finally seat the ball firmly on the charge. At this stage of loading, there should be no fouling at all left in your bore, and there will in fact be a thin film of lubricant coating the bore from ball to muzzle. I have read that there are some good commercial patches available, but they are so easy to make, it seems silly to me to buy them. I go to the fabric store, in my case, Fabricland (Canadian) with my Vernier's calipers and measure denim, drill, or twill fabric by crushing the material between the jaws of the calipers with my thumb and forefinger as hard as I can, and take a reading. This is how the patch is compressed in the bore of your rifle, so this is the measurement you need. I submit that your patches for a .50 cal rifle and a .490" ball should be no less than .018" thick (compressed) and better yet. 021". Here, denim fabric that is listed as 8 oz. measures .018" and 10 oz. denim measures .021". I precut my patches too, using a 1 1/2" ball bearing and a bearing race of the appropriate inside diameter. For a .50 cal, I cut 1 1/8" patches, having first washed and dried the material twice to remove the sizing in the cloth from the factory.
Wonderlube doesn't work, as you have discovered. Perhaps you can salvage it if you cut it with neatsfoot oil or olive oil by at least 100%. But the oil alone will be so much better than adding the Wonderlube. There are dozens of good lubes that all work more or less equally and a brief search here will find discussions on them all. For target shooting, as in sighting in a rifle, trail matches or just fun shooting, a liquid lube with a water base is all you need. But your patches must be close to dripping wet, not just damp. I place all the patches I am going to shoot into a copper patch box and pour my liquid lube into the box until it is about to overflow. I press the patches down into the liquid saturating them all, then pour off the excess back into my storage vessel, pressing the patches gently with my finger to squeeze out the excess liquid. I carry extra patches and a small jar of liquid lube with me to the range, in case I run out of patches and need to replenish my supply.
Now, I confess to using a short starter and a priming horn, so I am going straight to $#*! for blaspheming. But I can also shoot all day without having to wipe my bore. One of my favourite rifles is a Western PA rifle after T. Allison in .25 cal. and I use .018" patches about the size of a dime, a .250" ball, and my 1/4" wooden ramrod to load this rifle all day long. You cannot, I hasten to add, load the rifle in one long stroke as that would surely break the rammer, but instead, I use 5" lengths of the rod to push the ball down the bore, finally placing the hole in the knob of the starter over the end of the rod for the final bump. But for the purposes of target shooting on a firing line, and for cleaning, also use a steel range rod, even with my .60 cal Virginia rifle.
I apologize for the wordy missive, but sincerely hope that some of this will help you, and add to your enjoyment of shooting black powder longrifles.
