Hi Quick,
I see we are on opposite sides of the country and that you shoot F Standard. I shoot it too, at Belmont. My elevation suffered badly in the second stages. It was only after drenching the barrel in solvent and using one stroke/pass of the bronze brush for every shot fired, that it would hold elevation for two stages. If you think this is a lot of work, there is more to come. We/I detach the brush from the rod at the muzzle. The rod is not pulled back with the brush attached. By removing the brush, there is no risk of pin-pricking the bore at the muzzle, when the stiff bronze bristles reverse direction, to go back to the muzzle. All of this is best accomplished with the rifle immobilised, as in a vise on your work-bench, at home. Drenching is performed with a syringe. Suck in some solvent and attach a length of hose to the end. I use 5" of vacuum hose, which seems to fit in to the chamber easily. The muzzle should be a little lower than the chamber. Brush for ten strokes and wipe clean. If you have fired 25 shots that's how many times you're looking at. I use Pro-Shot. Wipe the barrel, finally, a couple of times. Apply Pro-Shot ON A BRISTLE BRUSH. Work it backwards and forwards, say six times. Leave overnight. Pro-Shot won't etch like Sweets and Bore-Tech. When you wipe out the next morning, the patch should be clear. Had you applied the solvent on the bronze brush, the patch would be blue, because it reacts with the copper in the bronze. For this reason, I wash my brushes with a garden hose.
Good shooting