Another barrel break in question

[model14]

How much difference have you experienced in group size as you break in your new barrel? Is there generally a large difference between the first 20 shots grouping and the180-199 shots grouping? Has your experience been different depending on the barrel and caliber? I am asking because I just finished breaking in my new 6.5 barrel (.260 chambering) and it has taken about 200 rounds to settle down to the expected sub-1/2 moa accuracy. It started at
1- 1/2 moa, or so, for the first 20 - 30 rounds, then just kept getting better. I think accuracy is where it is going to stay after 200 rounds.). My barrel is a Bartlein stainless steel HV.

 

[OldPPC]

My experience with break-in is that no two rifles respond exactly the same way. I've had them settle down early (at about 50 rounds) and late (in that 200 round region you've experienced) and I've found that the load, type of bullet selected, etc. dramatically affects break-in. For a new caliber I generally load something about mid range, fire off fifty rounds, the begin working on perfecting the load. By the time I've got the load worked out I have usually found a consistent 2moa group from which I can continue to refine all of those minute details that result in tighter groups.

 

[therifler]

bartlien barrel

i believe you are right about the 200 round figure or sooner then that . however changing the lenght after 1200- 1500 rounds by cutting back and rechambering may find you new and better accuracy.i know it did with my bartlien barrel . www,therifler.com

 

[Old Gunner]

I've occasionally run across mention of barrels which were manufactured with the edges od the lands already rounded off, about as much rounding as would occur after several thousand rounds of use.
Then I found an essay on rifling that stated that rounding of the edges would greatly reduce blowby, and cut down on deviation in velocity and reduce erosion.
Mechanical erosion due to bullet friction is very gradual and results in a fine taper to the bore. Old time shooters often preferred to use a slightly worn barrel that had been set back and rechambered to eliminate erosed throats. the very fine tapering effect was beneficial, the bullet being forced into an ever tighter space as it traveled, ensuring a tight fit and full engraving.