I have boiled out a couple of them myself, but I have also had some beatle work done also witch is nice. The biggest problem that I have seen with boiling is that over time the skull will start to yellow now matter how much peroxide paste/bleach you put on it.
Here is a picture of a Javelina skull that I had Skulls Unlimited do. It is over 10 years old and is just as white as the day that I got it back from them. I might have to check and see just what else they do besides letting the beatles suck the oils out of them.
Anyone who shoots a sabot bullet has had the problem with loading the next round with a dirty barrel we have all struggled with it.
Between muzzleloader shots I have done some research and testing on my own to find out what works for me for the next shot. I have been using a product called bore butter and when the muzzleloader is just sitting around I leave it caked in the barrel for protection. Have also found that if I lube my sabots with bore butter they really slide nicely down the barrel....