You may have some accuracy issues with the wheel-weights.
The reasons are two fold.
First: As the melt cools, w/w acts differently than pure lead. The wheel weight metal will expand and will "mike"out slightly larger. This makes seating the bullet in a muzzle loader "MUCH" more difficult. In the case of a front loading revolver, the amount of lead shaved may be asymetric and imbalance the bullet destroying accuracy.
Second: due to the hardness of the metal, it might not properly obturate to the bore (upset and expand) if the bullet is an undersized design such as the "Minie" balls. This will increase blow-by around the bullet by preventing proper sealing of the bore. This increases bore erosion and also is very detrimental to accuracy.
The additional cost of pure lead for the "charcoal" burners is well worth the trouble and expense for the increase in performance.
However, I've found an effective way to utilize the w/w metal in my "front loaders". I use a .50/.45 cal sabot and cast pistol bullets. I've found that the bevel based pistol bullet shoot best because they release from the sabot more cleanly with less "upset" in flight and give superior accuracy. Also, my guns are older and have 1/48" twist barrels so they give best accuracy only with "shorter" bullets, ususally 300gr and less.
Effectiveness on deer and pigs is excellent. All I've shot have been "DRT". You still can't argue against the effectiveness of a .45-.50" caliber projectile.