I have some room for an increase in pressure. I'm no where near max.
Two seperate rounds. 200 grn .45 acp and 180grn .40 S&W
Try working up the load to mid range and see if the leading decreases. If leading decreases, you are on the right track.
What would you recommend? I'm having the same problem using both Unique and Clays. Bumble Bee (hardness unknown but they seem pretty hard to my thumbnail) 240 gr. SWC BB. The last batch was using 10gr. Unique. What a mess.
Missouri Bullet 18 BHN:
200 gr SWC 45ACP bullets - about 5.0 gr of W231/HP38 produces no leading in stainless 3"-5" Kimber barrels (None). I get minimal leading in stainless Taurus Mil Pro PT145 at chamber end (leading readily taken out with 15 minute WD40 soak and copper scrubber on bore rod). I will pick up my new M&P45 in 2 weeks so I will report back on leading using the same load.
180 gr TCFP 40S&W - 4.3-4.5 gr of W231/HP38 produces minimal leading in G22/G27 with Lone Wolf barrels and M&P40 with factory barrel.
125 gr RN 9mm - 3.8-4.0 gr of W231/HP38 produces minimal leading in G22/G27 with Lone Wolf barrels.
Note: Kimber and Lone Wolf barrels used were all stainless barrels with polished rifling from the factory. I have noted more leading in other factory semi-auto barrels (M&P40/Taurus PT145) that have less "polished" rifling finish, but leading is readily taken out with 15 minute WD40 soak and copper scrubber on bore rod.
Disclaimer: Above results were from specified factory/after-market barrels I used. Results from your pistols/barrels using different OALs may vary (especially shorter than typical OAL).
Of course, you could just get the softer bullets.
I have shot 24 BHN bullets that a local bullet caster made for the past decade. He's retired and when my supply ran low, I tried MBC bullets and I am getting less leading with 18 BHN bullets. I haven't tried 12 BHN bullets, but I am quite happy with 18 BHN bullet results.