I don't have experience with your exact situation, but maybe I can tell you something that you want to hear...
Have you ever considered using cream of wheat in your lead reloads (I'm serious, not joking here)? I have done so with 357mag and 45ACP (I have a test bunch made up in 9mm with some 125LRNs that I haven't shot yet, but based on my other experience I am sure they will be just fine). I have also used cream of wheat with cast lead 7.62 bullets in 7.62x39 and 7.62x54R. Haven't chrono'd the rifle bullets yet but I suspect they were up around 1800-2100 fps. No leading at all, clean bores.
The theory is that the c.o.w. gets compressed up under the base of the bullet and acts as a gas check, preventing leading.
(THR thread on cream o' wheat) This plug of c.o.w. gets pretty darned hard and is also the bees-knees for cleaning out the bore of any leading that happens to already be there.
So I can't guarantee it'll work, but if it works in 7.62x39 with lead bullets (shot in an SKS by the way, and did not cause any gas system issues) I am quite confident it will work for you. The price paid other than the extra step in reloading is that so far my rifle bullet accuracy has been quite poor, which so far I attribute to the cream of wheat.
What I do for my pistols now is to make 10 to 15 of the rounds in a box of 50 with cream of wheat, mark them on the base with a sharpie, and then shoot them last. Totally clean bores very similar to the pictures in the linked thread. For 45ACP and 230 LRNs I use maybe 1cc of cream of wheat on top of the powder and then seat the bullet on top of that, compressing it slightly. The 9mm 125LRNs I've made up but haven't tested yet used a lot less c.o.w., maybe a little less than 0.5cc as measured by the Lee calibrated scoop method. That comes out to about 3 grains by weight of cream of wheat.
YMMV etc and no guarantees, but I would suggest giving it a try. With what jacketed bullets go for I would sure try it! If you do try c.o.w., you have to start working loads up separately since the cow may raise pressures, especially with fast pistol powders. I have successfully used it with W231 in pistol and BL-C(2) in rifle.