Bullshop has .504 conicals ready to go from the NEI mould #373. Weighs about 480 grains. His prices are great.

You might want to use a Maxi-ball or Lee REAL to check your bore size. That is critical for buying the right conicals. Just run one into your bore, then push it back out from the breech - mic the top band of the bullet to get your readings. Max reading will be groove-to-groove (or possiblly less than groove-to-groove if your bullet doesn't fill them) and minimum reading will be land-to-land measurement. Land-to-land is the dimension you will need.

You would then want to try a bullet that is just at your land-to-land measurement or very slightly over that measure (maybe .001).. Bullshop has a number of sizing dies and can probably fix you up. TC barrels vary enough there is not much predicting which will fit your particular barrel best. IF you happen tohaveone of those barrels where the QLA is a bit off center, lead conicals aren't going to shoot worth a hoot. PowerBelts might still shoot okay though.

http://bullshop.gunloads.com/index.html Thing about ordering from a caster is that you need the true barrel measurement as previously indicated, need to specify material as pure lead, and I would recommend you choose his Speed Green lube if you are shooting subs or his #2 lube if you are shooting true black.