Barrel break in accuracy

If they are key holing into the target, that's much more like that bullet not stabilizing and not the propellant/charge choice. I think I'd do a check of the barrel's twist rate with a cleaning rod to make sure 1 in 8 is actually what you ended up with.

Starting over with a ladder using your 120 core-lokts is a good bet. Cup-n-core being a much shorter bullet. My last new 25-06 barrel was a brux 1 in 10. Broke it in using 117 Sierra GK's with RL-22. Stayed fairly mild on the load until I had about 100 rounds through it, as it was still picking up a little speed each session. Stabilized around 90 rounds. Have had good results with Sierra 117 Pro Hunters as well as 110 Accubonds with RL-23 turning out to be the best powder in it at near book max.
I no longer have the factory barrel. The new Hart barrel is an 8 twist, and I'd say that is correct because so far, there's no keyholing whatsoever, the holes are nice little round holes, and first 3 shot group was 1 1/16 c to c, so things are looking up.
 
I no longer have the factory barrel. The new Hart barrel is an 8 twist, and I'd say that is correct because so far, there's no keyholing whatsoever, the holes are nice little round holes, and first 3 shot group was 1 1/16 c to c, so things are looking up.

Sorry, thought that's what you meant by hitting the target sideways. Sounds like its shooting now. Close enough to invest some time and effort to see if you can tune it in further with those.
 
Sorry, thought that's what you meant by hitting the target sideways. Sounds like its shooting now. Close enough to invest some time and effort to see if you can tune it in further with those.
We'll, I hope so. Them hammers aren't cheap, and I just bought another hundred. Once I get a load figured out with them, I'm going to switch to something cheaper until about hunting season.
 
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
 
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
Not the stock. It's a McMillan M40 HTG stock. Pillar bedded and the action bedded with pro-bed 2000. Not the scope or mounts. They've all been torqued and retorqued. It's just tuning the bullet to the barrel. It'll get there. There's only been 22rounds put through it, and none of them were tuned for this rifle.
 
Once you get "broke in" and done burning that 26 pixie dust, I would try VVN560, Rl-17, 19 or something in that range.
Curious. You getting good SDs in temperature below freezing with the VV N-560? I do with the N - 160. Have an opportunity to get a Kg. Of 560. Assuming they are similar in comp just the 500 series is a bit hotter.
 
If it were me the first thing I'd do is call Hart and let them have a look at it.

If it's a bad barrel they'll replace it.
This is exactly what I thought. That's y I asked about a borescope. Might save on material that's both expensive and increasingly difficult to predict availability.
 
It would make a lot more sense to stick to a hunting bullet he intends to use in the future.

At the price of bullets these days it doesn't make a lot of sense to buy bullets you don't intend to use up.

They may be cheaper than the Hammers but there are also other alternatives such as the Accubond and Accubond LR not to mention the Hornady ELD-X and SST.
Absolutely agree. I've switched to almost exclusively using Monos; Mainly Barnes LRX and Hornady GMX for all boiler-room shots. Or low weight for caliber headshots; 110gr in a 270 win for example. Black Bear is the exception. They get 160gr RN from the 6.5 creed. Interestingly they are one of the most accurate loads thru that Sako finnlight with its 20" SS 🖊 barrel.
 

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Absolutely agree. I've switched to almost exclusively using Monos; Mainly Barnes LRX and Hornady GMX for all boiler-room shots. Or low weight for caliber headshots; 110gr in a 270 win for example. Black Bear is the exception. They get 160gr RN from the 6.5 creed. Interestingly they are one of the most accurate loads thru that Sako finnlight with its 20" SS 🖊 barrel.
Doesn't surprise me. The 160gr RN has been an industry standard for 6.5's being used for large and/or dangerous game for a very long time.
 
Instructions I got from Hart was to go shoot it like normal. They said their barrels don't need a break-in period. Now In actuality, that may or may not be true, but that came directly from Hart.
That might be true from Hart. However, if the gunsmith worked the barrel then You should clean it thoroughly. Just my thoughts.
 
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