Take it from an old rimfire benchrest shooter, don't shoot a precision rifle real dirty. I always kept mine clean and just fired a few shots to foul (actually what you are doing is coating the length of your barrel with bullet lube) the bore and settle your rifle down. As my gunsmith who built several rifles that won National Championships and which set benchrest records told me. "You can repeat clean, you can't reliably repeat various levels of dirty." A rimfire chamber's leade will develop a carbon/lead ring over time and that is detrimental to accuracy. I always cleaned with a brass/bronze brush to keep that lead/carbon ring in check.
A new rifle's bore can be a bit rough. We would shoot a brick of ammo thru our brand new rifles before getting serious about accuracy. I would also put some IOSSO paste on a patch and stroke the chamber area for the first couple outings/cleanings to smooth out any rough spots from cutting the chamber. Also, a precision rifle with a match chamber will perform best with std. velocity match quality ammo like Lapua, Eley, SK and RWS. And, believe or not, std vel ammo actually bucks the wind better than HV supersonic ammo.
