If you are getting slight streaks (I do). Try pulling out your bore guide, clean/dry the chamber and first quarter inch of your throat with a t-shirt wrapped around a pistol rod.
Then put the bore guide back in and see what you get. A little in gray is ok.
As mentioned the quality of barrel manufacturing really helps. I just got an x-caliber barrel and it doesn’t clean up easy AT ALL!!!
You guys need to try this. A fine barrel maker gave this advise and I have been using it ever since, wondering why I didn't do it a long time ago!
He said to simply start a bore snake weight down the barrel, from the chamber, squirt 7 or so drops of oil in and pull through. That gets all the fouling you need to remove and wets the barrel. He also said to never shoot a dry barrel. It is simple and very effective. No loss of accuracy. You also don't need to do this very often neither. I have gone over a hundred rounds before snaking it again. It's like when ever you want to do it. Honestly, it works! Benchrest shooters do what? Clean the dickens out of the barrel and then shoot several fouling rounds before going to the record target! Duh! Same principle!
I have a Rock Creek barrel that will have patches come out as clean as they went in. I have a Vanguard that will have a couple gray streaks, I also have a Mosin that makes almost black patches no matter how many I put through.
I’m missing something here...
Never shoot a dry barrel?
I was told by a fine barrel maker not to shoot a "dry" barrel. Fouling is "wetting" the barrel, as is the thin film of oil left over from a bore snake pull through. Makes sense to me. I mean, the two surfaces being dry will "tear" at each other as a bullet (and hot gases and burning powder) passes through. Think about a frying pan, some foods will stick to those dry pans, but some oil sure helps to minimize it.
There is a lot of factors that come into play when cleaning. How long since last cleaning, quality of the barrel and also quality of the machining process when rifling the barrel. If you are running a brake also check that as it will give you some black marks on exit as usually all your solvent builds up right outside the crown where the brake meets barrel in that small difference in diameter. I am totally ok with small amount of streaking. Once I am done I always run one patch down with a lubricant such as remoil or similar and then run one dry patch after that. Always had gun luck with this process.
I have heard not to leave anything in the barrel as when the bullet goes down it, any "wet" residue is not displaced fast enough and it can warp/cause problems with the barrel staying true...Is this accurate, I don't know, but I am not willing to test on my barrels, so I just dry em out. If going in storage for long term, I put some lube down them, but dry em before shooting.
I am pretty fanatical about ensuring the bore is dry after each cleaning session.