I've noticed a slight bit of leading in a 9mm when shot with reloads. The leading I speak of almost looks like a rifling groove (in that it's a streak that is parallel to one of the rifling grooves for most of the barrel), and usually goes for at least half to two thirds of the length of the barrel. It requires a pass of a bronze brush about 50 times to clear out after shooting off 50 to 100 rounds.
The reloads I am using are soft target loads. 115gn SWC - .356 in diameter, coated with lubricant and travel around 860fps.
I was wondering for this type of shooting if this is the wrong size? I've done a google search and see that some people use .357, even .358 sized bullets in their 9mm. Does larger diameters on slower loads reduce leading, or can someone point me into the right direction of what else could be causing this / what I can look at changing to reduce this?