I used to shoot the ball-et in a tight-bore Traditions Deerhunter and it was ok...but just ok.
My guess is your problem is a fairly loose-fitting bullet combined with 209 ignition. The ball-et has a short bearing surface (ie the length of bullet that contacts the barrel) compared to most conicals. This means it will create less resistance to being pushed down the bore by the ignition.
209 primers are a poor comprimise sprung out of convenience, not because they are ideal for use in muzzleloaders. Look at the tiny primers used in high power rifles compared to that monster 209. The reason is, in a shotgun, the powder must be fully ignited and build pressure before the crimp on the shotshell breaks open, since the shotgun wad/shot column form a very poor seal as they fly down the barrel. This requires a lot of flame! Hence the 209 design. In a regular rifle, the bullet creates lots of friction as it has a tight fit all the way down the barrel...so the powder is ignited and burned more gradually as it has the barrel length to combust.
In a ML, 209s are WAY overkill. They are much more like a rifle than shotgun, yet 209 primers are self-contained and are big enough to insert and remove by hand. This is the ONLY reason why they became popular in muzzleloaders. As Redhawk and I can attest, the conversions available to use rifle primers in ML rifles work wonderfully.
Back to your case. When that 209 goes off, it has enough power BY ITSELF to blow your bullet from the barrel!! If you don't believe me, try firing a load without powder (but just in case, do it in a gun you can push the load out through the breech if I'm wrong!). I've seen this happen. Likely, your ball-et did not create enough pressure to let the pyrodex ignite and combust correctly before the 209's power blew the whole load down the barrel and out the muzzle. Try a longer conical or stay with sabots and you shouldn't have a problem.
I am certain there is nothing wrong with your equipment. That's my opinion!
