Comments on: How Barrels Can Yield More Velocity After 100-150 Rounds

By: Jim See

Jim See — Tue, 21 Jan 2020 01:32:34 +0000

A link to a video I did tonight after a FB discussion about this accurate shooter article.

https://www.facebook.com/jim.see.739/posts/2985174281517402?comment_id=2985184641516366&notif_id=1579569557704228&notif_t=feed_comment

By: Adam Bentley

Adam Bentley — Tue, 21 Jan 2020 00:26:41 +0000

To piggy back off of Practical Tactical, steel does two things under heat and pressure, harden and erode. The virgin steel is hardening and reducing the friction coefficient between the bullet and barrel.

By: PracticalTactical

PracticalTactical — Fri, 31 May 2019 16:28:05 +0000

If you Google
coefficient of friction steel
coefficient of friction copper

You will find the answer…

The coefficient of static friction for steel is around 0.6–0.15

With very clean surfaces, the coefficient of friction was 1.0–1.1 for the entire load range.

A new barrel has not been “Copper Plated” yet and therefore has greater friction than it does after copper build up has occurred.

For this reason if you clean a barrel “too well” it will shoot squirrelly for the first few shots, then settle down.

By: David Lawson

David Lawson — Fri, 31 May 2019 02:04:48 +0000

The heat and the slight glazing of the barrel although very tiny would account for the increased velocity.
Shooting in, in even a match grade honed barrel will happen by physics alone.