Adirondaker,
I think the reason there is disagreement about the effectiveness of some lubes over others is variation in barrel condition. I recommend you firelap the barrel. I had an M1 Garand barrel that would foul jacketed bullets so badly that it required 120 strokes with Iosso Bore Paste (the most aggressive of the abrasive bore cleaners) on 4 different patches, plus 20 patches soaked in Sweet's 7.62 ammonia bore cleaner to get it clean. After firelapping it took only 10 strokes with the paste on one patch and no Sweet's and it was clean. Alternately, 5 patches of the Sweet's and no bore paste would do the job. I have a Hawkeye bore scope, so I could really see this was true.
The same applies in spades to cast bullets. After my Garand experience, I have firelapped all my guns that don't have hand-lapped custom grade barrels. And even those, when throat erosion has roughened them, respond well to a bit of light firelapping to clean them up. After that, many lubes appear to be more effective than they once were, and you will only require the best lubes for light bullets at the highest velocities.
You should also take a look at the semi-permanent barrel lubes, like Sprinco Plate+ or Shooters Solutions' Moly Fusion. Or even the old Microlon treatment. All cause velocity increases by reducing the same barrel friction that causes metal fouling. Firelap first and foremost, then try one of these lubes. You should need only minimal bullet lube afterward. WARNING: don't get even a trace of these lubes in your chamber, or excess bolt face pressure can result! They are very difficult to remove.
One reason for shooting bullets as cast is that sizing disrupts the crystal structure at the rifling engagement surface. This causes loss of hardness at that surface that doesnt complete until, like a spring taking a set, the metal has time to relax the stresses caused by the sizing. When you let the barrel do the sizing, the bullet gets out the muzzle before the stress relaxation can occur. This is like shooting a harder alloy after normal sizing. This goes double for water-hardened bullets. They have more stress to relax.
If you read Lyman's Cast Bullet Handbook, you'll see a description of water hardening bullets. They are sized and gas-checked first, then hardened, then lubed in an oversize die that doesn't upset the surface again. That's how you may both control bullet diameter and retain full hardness.
Nick
Nick