I am a big believer in barrel break in for many reasons as discussed in the past.
The benefits in reduced fouling along with longer barrel life and faster load work up make it worth while in my opinion.
But today, I wanted to see if there were any more benefits to barrel brake in so I performed a test that I had not seen anything about it and this is the results.
I built myself a 260 AI using a 788 rem action and a 3 groove Lilja varmint contour barrel.
The loads were fire form loads in the middle of the 260 loading using a 123 Hornady match bullet.
The test was to chronograph the fire form loads as I did a breakin of the barrel to see if there were any changes in velocity during this process.
Here are the velocity readings.
Clean barrel
1st shot = 2790 ft/sec
clean barrel
2nd shot = 2808 ft/sec
clean barrel
3rd shot = 2831 ft/sec
clean barrel
4th shot = 2854 ft/sec
clean barrel
5th shot = 2868 ft/sec
clean barrel
6th shot = 2878 ft/sec
clean barrel
7th shot = 2890 ft/sec
clean barrel
8th shot = 2894 ft/sec
At this point the barrel appeared to be broke in because it cleaned up well and velocity seemed to remain close to 2890 ft/sec with SDs below 8.
There was no point to figuring SDs during break in because the velocity kept climbing but once it settled down SDs were good (Especially for fire forming loads)
Velocities during break in had a 104 ft/sec total spread but once break in was finished, the average velocity improvement over the first round was averaging 80 to 85 ft/sec faster than the first shot in the new barrel.
This was just one test and i am sure some barrels will exceed this improvement if break in is done correct and some will not, but it does show me that there is another advantage to doing a breakin beside less fouling.
I don't know what a barrel would do if it was not broken in, or when or how many shots it would take before it would reach its average max velocity from the first shot.
NOTE: All loads were as exactly the same as I could load them, so I feel the test was valid and at least I learned something from it.
J E CUSTOM