Help me understand leading-no leading problem

[ButterNutZ]

Recently I bought a Taurus 605 in 357, loaded some rcbs 38-140 gr bullets that leaded the barrel badly. (here is the original post I made click here (http://castboolits.gunloads.com/showthread.php?178729-Taurus-605-leading)). Well after some more tinkering with load I saw no improvement. Finally I decided to load that 140 gr pill with a stiff load of H110. That load produced velocity of 1050fps out of the 2 inch barrel and had zero leading. The bore looked shiny like a mirror after 50 rounds of those stout magnum loads. I'm kind of scratching my head here a little bit. Does the magnum load drives the bullet that much harder that it plugs the bore better, or does it have an effect on some what of a hard lube that I use?
What say you?

[nhrifle]

Sometimes we learn things in this obcession that are counterintuitive and don't make sense at first. First thing I think is happening is that the H110 load is probably working at a better operating pressure for your revolver, and obturating the boolit to fit the bore better, making for a better seal. Second thing, the H110 load might have a pressure wave that works better with your alloy. Think of it like this: a very hot, sharp smack of powder blast from a fast burning powder can theoretically shock and vaporize the base of the boolit, allowing it to deposit in the bore. The H110 is a slower powder than Unique, and gives the boolit more of a shove than a punch.

[runfiverun]

hard lube is better suited to high pressure.

[44man]

H110 just spreads the pressure peak a little instead of all at once. Your boolit will be in the rifling and engraved before max pressure arrives.

[ButterNutZ]

Well guys that makes perfect sense. The bullet is in the rifling before the peak pressure is built up. I would have never guessed that one. I'm gona add a bit more ATF and maybe some ALOX to my lube making it softer and see how that effects my Unique loads. Come to think of it I never saw any lube build up at the muzzle with those lighter loads, but after shooting the H110 there was plenty of lube residue deposited.
Any who thanks for explaining it.

[1bluehorse]

I did not read the first post you wrote. All the above are good answers and probably fit the question. Assuming the Taurus's cyl. throats and bore meet the accepted criteria for shooting cast bullets and the bullets are sized to fit said dimensions..?? For me, and I know there are a lot of folks who may disagree, or haven't had the same results, (just read the lube section) but all I ever use for pistol lube is 50/50 and have never had any issues for my applications. That would be 357-44mag-45 colt..these all from mid to full power loads..however I don't have some of the "extreme" weather conditions some have. Glad you're making progress with the 357..

[captaint]

NutZ - Lube aside, you might have to make your boolits a little larger diameter for your lower power loads. Plus .001 might well do it. Just a thought. Mike