Some of the makers of very fine barrels recommend a break in proceedure,and they describe t for you.I have read Gale McMillan's advise on the topic,and won't argue.
If you are working on the tailgate of a pickup,balancing the rifle on your knees without a bore guide ,etc,could be you will be doing more harm than good.
I compromized and pulled a new bore snake through a couple of times with a little "PatchOut" on the leading end.I did this between each shot for the first 10, then between each of the next few groups.
Did I do any good? I do not know.I felt better.