There's a variety of bullet lubes,
natural and commercial.
Without trying to get too technical
or provide you with complicated recipes,
some folks simply fill the grooves with
Crisco, which is vegetable shortening.
That is, it's made mostly from oils that
are solidified for storage purposes, and it
can be melted for cooking/frying.
This can also be melted and blended with
about 50% bees wax to create a better lube
with a thicker consistency.
Most folks just use a commercial BP patch
lube like TC Bore Butter or its equivalent,
Traditions Wonderlube. These come in a tube
and are soft. They're mostly made of mineral
oil and a micronized paraffin wax.
Basically any vegetable oil can be mixed
with bees wax to make a bullet lube. Just
avoid using petroleum products as a lube
which will react with BP to form a tar which
will foul the bore.