es,
Piostalchamp has a good idea and I have seen people use a sheet of bees wax or lube to protect the base of the bullet. Just push it into the case (the case acts as a cutter) and seat the bullet.
I really think at the velocity you will be getting with the 577 you shouldn’t have a big problem with leading as long as your bore is ok. If your bore is to rough gas checks will not help. Try the water quenched wheel weight lead it should be just fine. If you have been loading for rifle with lead you know the better bullet lubes to use.
What load are you going to use? What load is your rifle regulated with?
Bill