Curtis, it's hard to answear your questions without seeing what you have but I'll give it a shot. If the bullets weigh a 160 gr. they are probably from a Lee mould. For plinking you want hard bullets. If you can't marr the lead with you finger nail that would be good, if you can marr the lead, it still may work ok. If it is a Lee bullet, the fact that it weighs 160 grs. tells me that there is a fair amount of antimony in the alloy. It would weigh more and be softer if the alloy had less antimony, like wheel weights.
The lube is good if it's not hard as a rock. If it is, use your finger nail and remove it. Get a stick of bullet lube, warm it a little to soften it some and smear it into the bullet grooves with your finger. Remove the excess lube by holding the bullet nose and push the bullet into a fired, unsized 30 caliber case. This will clean off the excess lube level with the driving bands.
You can flair the 30H case with a spitzer bullet of a larger caliber, such as a .338". Just place the nose of the .338" bullet into the mouth of the case and tap the base of the bullet a few times with a hammer. Trial and error will tell how hard and how many taps you need.
Cast bullets will shoot better if the gas check is held in the neck. You lose accuracy if the gas check is into the poedwr space. The 30H has a fairly short neck, but it most have a fairly long throat. You will just have to play with the seating and get the best that you can.
For powder I would try 18 gr. of IMR 4759 or 19gr. of IMR 4227. Both of these loads are near max.
