I personally think you simply need to bump your charge weight up a touch. Maybe load up 20-25 rounds in 3-5 round groups with the charge weight increasing around .2gr at a time and see if it slows down or stops. It wouldn't take much to get the pressure up to match the alloy hardness. Once there no more leading.
Having said that, I pulled this short list down from one chart,
# R-1, Norma
# VV N310
# AP-30N (ADI)
# Bullseye, Alliant
# Titegroup
# AA #2
# Clays
# Red Dot
# VV N320
# HP-38
# Win 231
# Trap-100
# Hi Skor 700-X
# Win 452 AA
# Green Dot
# AS-50N (ADI)
# VV N330
# PB, IMR
# AA #5
# Unique
# Hodgdon Universal
Moving down the list from the top to bottom is relative quickness of burn rate. It is pretty clear that Bullseye, Titegroup, AA #2, Clays, Red Dot, and Win 231, are all listed as "faster" than 700. However I have shot plenty of loads with all of them and experienced no leading in my Colt Govt 1911 or my 1991 A1. These were used with bullet weights ranging from 200 up through 230. However by the same token I have also leaded up my barrel really nicely using Unique, as well as a couple of the above mentioned ones as well.
Usually when the leading is in the lead area of the barrel it is related to either size or alloy. Since your size appears to be correct, your alloy is probably harder and needs a bit more punch than your giving it.
With just a little bit of quick reading on the following link, you should be able to see exactly what I am referring to.
Cast Bullet Notes
Also when referring to powder, quick is a relative term. When loading for cast bullets you will find that in most cases those "quick" powders will usually end up working out better, than the "slow" ones.