Why are black boolits brown?

[KYShooter73]

I have been putting hi-tek through it's paces lately. Hi-tek black, al GC @ 1800 FPS, 300blk. Nice groups but I have dark residue in the barrel. My specific question is after 3 good coats (each coat tested with acetone and hammer), why are my "black" boolits dark brown after three 3 baked coats?

[popper]

I tried the green in 30/30 @ 1300 and got a hard ring near the muzzle. Had to pound a triple patch & choreboy wrapped brush through to remove it, and I mean POUND. What boolit are you using?

[kweidner]

I suggest you email Joe. He is great about responses. Mine look brown in sunlight after 2 coats but with three they are black. Temp swings will turn em brown if oven gets past 390 in my experience. This is precisely why I own Brevilles.

[KYShooter73]

I'm using a Lee 312-155. I am using a cheapie oven, same one I use for PC. They are straight COWW sized to .311.

[Ausglock]

5.1.5 makes black bullets. 5.1.7 and above makes brownie black bullets.
It is the yellowing of the resin at thinner mixes that does it. 3 coats of the thinner mix fixes it.