Are you sure it is the bore of your new barrel, could it be your stock, or something else? You might have checked all these things already but it is something to think about.
I suggest you methodically eliminate things so you don't chase your tail for months. I have had trouble for years with new rifles and barrels but recently I changed my approach after a old gunsmith from the UK suggested I read a book by Nathan Foster called "Bolt Action Rifle Accurizing & Maintenance". Nathan is from New Zealand and has spent decades learning and teaching others how to hunt at long range. I don't agree with everything he says and realize he is going against the grain of most modern / PRS long range shooters. However, the engineer in me likes his methodical step by step process. I found using his approach with a 2.1 MOA rifle actually had a stock issue not a barrel or load problem. I bedded the stock as he suggested and it went to 1 MOA then got better with hand loads. I never would have caught this issue if I had not used his approach.
I see break-in as critical and every rifle is different. I now use more of a cleaning and polishing method I learned from Nathan at break-in vs my old shoot 60-80 rounds then hand load because it takes less time and cost less money to get to sub MOA.
Nathan's views are controversial because he suggests a methodical method of break-in that includes lots of cleaning, maybe some throat polishing and even hand lapping with Scotch-Brite poly pads with a high fowling bore. He also pushes a through examination before he begins to fix a problem rifle - which caught my stock flex issue.
His book is long - 300 plus pages - but hunting long range is hard and I've found there are no short cuts