I've seen this before...Cay makes some good points, as does hunting junkie...I'd also add, check your crown at the muzzle...You have one patch at the top that is cut a thicker patch can actually be cut worse since it's tighter...I have recrowned some barrels to keep this from happening...

Also, you are comparing 2 different make patches one could have weaked from the lube and sitting on the shelf too long...I used to shoot store bought patches and lube but when my .54 started burning patches like yours is, I changed...This is the only way you can control the quality of patches and the way your patches look you will never have good groups until you fix it...

So, polish up the lands on the muzzle, buy some cotton ticking or drill cotton drill, make your own lube...btw, my .54 burns patches lubed with bore butter...But with homemade lube they are good...

Also...Go to either Pryodex or Goex...I know there are guys that used 777 with prb, just as some use Pyrodex for flintlocks but it causes more problems than its worth...

Once you find the right ball/patch/lube combo you will not need an insulator between powder and ball...