I use powder coat for full power handgun magnum loads (lots of guns) and typically have no trouble working up combinations that produce no leading.
I use a tumble lube (BLL) for milder loads that do not need the powder coat.
For 45 ACP (you said 1911, so I am assuming 45 ACP), the tumble lube worked great with target loads in both 230 RNs and 200 SWCs.
Leading in a 45 ACP with coated bullets either means bad coating (not likely) or "bad fit". If you are leading, the most likely cause is that your bullets are smaller than the barrel bore. The "standard" 45 ACP will be 0.452" and this is what you get with regular mail order bullets. Your reloading operation may also size then down just a little bit (if they are a tight fit in your cases). Your gun may be just a tad bigger than your "as loaded" bullets.
Of course, slugging the barrel is the obvious recommendation at this point. Cast bullets should be just a little bigger than the bore. Many bullet sellers will supply 45 ACP bullets that are bigger than the standard. If your gun is leading with 0.452" bullets, and you do not want to bother slugging the barrel, you could just try some sized to 0.454".
If you neglected to tell us that you 1911 is not 45 ACP, then please fill in the missing info. If you are shooting a 9mm (the all time champ for causing problems with cast), then I have a totally different slant on the same basic problem.