I'll call BS to the temperature of Titegroup causing the "leading". If you are truly getting real leading, something is grossly wrong with the bullets. The smell may be flame cut polymer coating. The flame never stays in contact with the bullet long enough to melt the lead even with bare lubed lead bullets. A typical pistol bullet in a 4" barrel exits in less than 4 milliseconds. The big problem is FIT. If the bullet is smaller than the grooves of the barrel, you will get gas cutting of the bullet around the gaps. Plating and jacketing will cut less than lead or polymer. Lead is the softest and most vulnerable to gas cutting.
Are you having problems cleaning the fouling up? Try running a patch with your favorite cleaner through the bore. If it cleans out easily, you don't have a problem. If that doesn't work, try a bore mop with a couple of strands of Copper Chore Boy or bronze wool. If the dust comes out is sparkly, it's lead and there is something definitely wrong. Before I took up casting, I noticed that Bear Creek Moly Coated bullets tended to smear polymer on my barrel grooves but it cleaned up easily with the bore mop/Chore Boy.
I tested some Titegroup on Friday with my M&P 9. My barrel slugged at 0.3545" and I used powder coated bullets sized to 0.358" seated to where the cone meets the case rim so than none of the 0.358" part of the bullet sat above the rim. I also used a 38 S&W expansion plug in the 9mm PTX die to open the case up before seating and the Lee taper crimp die (NOT the Factory Crimp Die) to close the flare. I used some surplus Sherwin Williams powder @ $2/#. The pigment is uneven, but the coating gives 100% coverage.
You can see the slight bulge of the brass where the bullets are seated. Yes, the bullets still pass the plunk test and headspace on the rim
I was more interested in the MV so I only tested 20 shots but this is what the barrel looked like when I brought it home.
20 shots 3.5g Titegroup= 1099 fps ave. MV, 3.7g Titegroup = 1117 fps ave. MV
I simply took a piece of paper towel, wadded it up and pushed it through the barrel once with a rod.
You can see a section of the paper towel below the barrel at the 4 o'clock position
FIT IS KING. You might be able to get away with a slightly smaller bullet if it bumps up due to pressure. Jackets, plating or powder coat help resist gas cutting, but sealing off the gases is the best way to prevent leading and metallic fouling in barrels.
If you ever intend to shoot anything other than jacketed or plated bullets, get some egg sinkers, slug your barrel and be aware that using bullets smaller than the groove diameter might give you problems.
