I have a Remmy SPS Varmint in 204 Ruger. This rifle likes being fouled. I quite the deep cleaning after quizing some of the senior posters here in TFL. My SPS was the same way as yours, I could never get the patches to come out clean, and every time I cleaned it for the first 400 rounds or so, the patches looked like they had been dunked into India Ink. Even after cleaning if I ran another patch with Hoppes #9 down the bore it came out black.So now a wet patch, a couple of dry patches and it goes in the safe. Don't care if the bore is not spick and span---what I want is a shooter.
Long story short--the best round took a while to find. Don't give up---heck if you like to hand load and like to shoot it is all a good time.