[Unclenick]

Could also be graphite from the powder stuck to a streak of bullet lube. No way to tell.

IME, even guns that don't continuously build up lead still get a bit. I've shot over 3,000 rounds through my 1911 without cleaning just to see what happens. Powder fouling cakes up everywhere until the gun finally can't close fully against it anymore, but the leading I got were a few streaks at the inside corners of the rifling in the throat, and, once established, they seem to wear away as fast as they accumulate, so equilibrium is reached and they don't grow and they're not causing a problem.

My Redhawk's bore is a good bit rougher than my 1911 barrels. It also had a slight constriction at the frame, which is fine with jacketed bullets, but prone to developing lead build-up beyond that point, and that required lapping out. Get a flashlight you can shine into that area in front of the throat. I use one of the flashlights with a bent Lucite rod on it to illuminate inside the bore.

Note that the .44 Magnum standard COL is 1.610" and the .44 Special is 1.615". Essentially the same length. That's because Elmer Keith developed the bullets and high pressures in heavy frame .44 Special revolvers originally. The longer .44 Magnum case is just to prevent the higher pressure commercial loads from chambering in a .44 Special chamber, where, with a light gun, they could produce catastrophic failure. But what the shared dimensions also mean is same bullet seated to the same COL will have about the same powder space in both cases, so you can use the same load data with both cases if your bullet has a crimp groove in the right place for the longer magnum case. A number of .44 bullet designs have two crimp grooves, one for the Special case and one for the Magnum case. Some manufacturers claim to thicken the magnum cases a little more near the head, but the extra pressure that would cause with a .44 Special load won't bother a revolver designed for magnum pressures.

Additionally, the Redhawk has a 1.75" long cylinder so that even if you use a .44 Special bullet with only a .44 Special crimp groove in the longer .44 Magnum case, it will still fit, though you might need a touch more powder to hit the same velocity.

What I am getting at with all this is that I prefer to use magnum brass even with Special level loads. The reason is the shorter case can allow some lead and fouling build-up from its mouth forward in the chamber. If that gets thick enough it can interfere with chambering magnum loads or make the ends of the cases fit so snug they can't release the bullet freely, raising pressure. So you have to be careful about that build-up in the chambers if you use the shorter cases. It's the same with .38 Specials fired in .357 Magnum revolvers. Anyway, I just take advantage of the longer cylinder to use the Magnum brass with all loads I put through mine.