New Barrel - Need to Re-tune after 200 rounds

[toasty]

As I have mounted and shot more new barrels, I am starting to notice a trend and wondered if others see this as well. I get a new barrel, do load development and get the powder and depth tuned up nicely, hopefully in somewhere between 50-100 rounds. It is not long after that, maybe 100-200 rounds that my load falls out of tune. When I test velocity, it is running about 30-50fps faster than my load development. I drop powder down and usually seat a few thousands further out and I am back in tune.

Is this normal? Is there a point where the velocity stops creeping up on a barrel? How often do you guys check the tuning on your loads? I am a varmint hunter and usually don't shoot paper until I notice some crappy results in the field. Perhaps, I need to be shooting paper every hundred or so rounds.

 

[SGT. Slaughter]

That happens generally with a cut rifled barrel, it tends to gain velocity until you get a 100-125 rds down the tube and then it usually settles down. I don't know how button barrels act since I haven't shot a button barrel.

 

[Clancy]

I’ve seen it as early as 60 in magnums and as late as 350 in a small 6mm, but MOST barrels will speed up after some rounds, yes.

There’s no set number to it so just watch your chrono and adjust if or when it speeds up.

 

[Straightshooter1]

As I have mounted and shot more new barrels, I am starting to notice a trend and wondered if others see this as well. I get a new barrel, do load development and get the powder and depth tuned up nicely, hopefully in somewhere between 50-100 rounds. It is not long after that, maybe 100-200 rounds that my load falls out of tune. When I test velocity, it is running about 30-50fps faster than my load development. I drop powder down and usually seat a few thousands further out and I am back in tune.

Is this normal? Is there a point where the velocity stops creeping up on a barrel? How often do you guys check the tuning on your loads? I am a varmint hunter and usually don't shoot paper until I notice some crappy results in the field. Perhaps, I need to be shooting paper every hundred or so rounds.

Yes, I'd say is pretty normal, based on my own experience and what others have said too. I've been using Krieger barrels and it's taken me ~150 rounds for the velocity to speed up and level off. This is why I'll use this time to fire form my cases with fully loaded cartridges (though not my best bullets) and afterwards do my load development. Though a new barrel seemed the same as the one before, it still took adjustments to the load to tweak it back to shooting like the previous barrel.

 

[toasty]

Thanks guys, I am glad I did not imagine this issue. My new 222 shilen barrel lost tune at closer to 250-300 rounds. Sounds like there isn't an exact number and typically, the smaller the cartridge, the longer it could take to settle in.

With the small easy, and fast Garmin Xero, should not be an issue to run a few every time out and check to see if velocity matches load development numbers.