Weeellllll since you asked
I’m a precision rifle guy and have been for fun and business for a good many years. In the case of a new to me rifle I will do what you are attempting to get back down to a “nothing but steel” barrel before I start breaking it in again.
This is where I depart from normal gun culture. I DO NOT clean my rifle barrels after they have been shot and zero’d UNTIL the accuracy of the rifle becomes unacceptable which to me is approaching 1 MOA (Minute of Angle) or 1.047" @ 100 yards or 10.47" at 1000 yards (OK I fibbed if my rifles get near 3/4 MOA they get cleaned the math is just easier at 1 MOA). How long does it take to get to that level? Well, my precision 30-06 gets cleaned after about 1000 rounds, my precision 308’s get it at about 1200 rounds. My 300WM’s usually the barrel is gone before it needs cleaned. For the bigger guns like 408’s, 416’s and 375’s it’s north of 750 to 1K rounds.
Here is the reason why and maybe this has happened to you. You scrub up your shooty stick and go to the range.
You get all hunkered down and squeeeeeeze the trigger BANG! 4" high and right. You think to yourself “I must have jerked the trigger.” You squeeeeze the trigger again, BANG. 2" Low but centered. This will continue on for at least a box of ammo and longer if you started playing with the scope knobs. FINALLY the thing begins to settle down and you are getting rounds pretty close to where you had it the last time you were at the range. Long about 50 rounds into it you are making one hole groups right where they are supposed to be. You are thinking “Man I’m out of practice and just needed to warm up.”
Now that you are all pleased with yourself and your rifle again you take it home and clean it. The next day you get lucky and get to go back to the range felling good that your trigger finger is right and you KNOW your rifle is sighted in.
Re read the paragraph before the last one, as this is what you will experience, AGAIN.
Why you ask? Because you scrubbed (incompletely) the copper PLATING that you put into the gun the day before and because somebody told you to, you put OIL in the barrel. Oil is a fluid and even if you wipe it out it is still there (unless you squirted brake cleaner down the bore which is a really bad idea unless you are trying to really clean the gun) you can’t evenly compress a fluid, by most accounts you cant compress a fluid at all. So until you burn off the oil and start laying down NEW copper plating which fills in all the little nooks and crannies in the steel your accuracy will suffer. As the copper lays down the accuracy will tighten up usually around 30 - 50 rounds.
As long as you are shooting modern ammunition with current powder and primers your bore will not rust, copper does not rust but it does oxidize so if you leave it for a year or so it might be a good idea to send a few rounds down range (or into the dirt) before you get serious with it. The most important shot out of a rifle is the FIRST one. The most telling thing about your rifle is the LAST shot. If you don’t screw with the bore, your last and first will be in the same place. Clean it and there is no telling WHERE that next round will go. I know that concept is a big pill to swallow but if you have back to back range days, TRY it, I’m sure you will be pleased with the results.