Mate i usually clean my 17 hmr after around 2-3 boxes of ammo(60rnds)
1. run an oily patch through the bore and let it soak for around 10 mins
2.copper brush 5-10 strokes then pass dry patches to remove powder residue untill you get a clean one passing through.
3. soak a patch with M-pro 7 copper remover(great stuff.made by Mc Millan Bros.Sniper rifles)and let it soak for 15-20 mins then pass dry patches through untill your patches pass through clean.
Youll be amazed how much shite the m-pro 7 removes...
You will here loads of different methods of bore cleaning.This one works for me.get