New Barrel Velocity Increase at finish of Break in?

[NW Hunter]

Hey Guys,
I've got 50 rounds down a Bartlein 5R barrel now for a 300wm using 185 gr. Berger hunting VLDs and 82.8 gr of H1000. I'm getting 2930 fps average with a few at 2960 toward the last of the 50 rounds.
I thought I saw a post somewhere here about a new barrel increasing velocity until it was totally broke in; maybe by Coyboy?
I've got a load worked up and was going to start shooting with a drop chart. How much velocity change can I expect for the barrel?

 

[Coyboy]

NWH,
I did make light of it in this article and some other posts.
Custom Barrel Care At 17X

I can not give you any definets on your velocity increase. With the numbers of rounds you have thru your gun I would suspect that it is at or near the point where it should be settling down and giving you some better numbers.

 

[NW Hunter]

Coyboy, thanks for the reply. I'm going to chrono velocity while shooting my drop chart numbers. this forum has really been a great learning tool.

 

[NZ Longranger]

The issue here is pressure. If you're already running right up there pressure wise with your chosen load from the start, then you need to be aware that with most of the larger long range cartridges that your throat and the first bit of the barrel will roughen up a little somewhere between 25 to 50 rounds. This roughening will require you to drop your charge a grain or two to keep your pressures safe and velocities the same as when you started. The barrel then seems to settle and your load will stabilize for most of the rest of your barrel life. We always shoot the rifles we build for our customers long enough to get to this point. By the time we've broken the barrel in, done a close range load development, and long range validation, we're usually there. You don't want this pressure spike to happen halfway thru the first batch of ammo you've loaded and given to a customer!
Greg