Barrel break in, myth or reality?

Is it necessary to break-in my new rifle?

Each week people ask me this question, and every time I say yes. Some call this procedure break-in, others lapping. . . Either way, if you buy a precision rifle or if you replace the barrel of your rifle with a high-quality barrel, it is recommended to make a good start (what is called the break-in) before using it.

Why?

The purpose of this procedure is to ensure that your rifle's barrel maintains its accuracy, and to facilitate its cleaning throughout its lifetime. To better understand its importance, it is essential to know what happens when you take your first shots with your rifle.

First of all, there is more than one reason to break-in a rifle, but the main and least known is that when your gun was chambered, the gunsmith used a piece called a reamer (refer to item 1 below) to pierce your barrel. This reamer corresponds to the cartridge calibre and shape that will be inserted into your rifle chamber.

The transition zone between the hole made by the reamer and the bore is called the throat (see item 2 above). It is at the end of the throat that the grooves of your barrel (rifling) begin. Chambering with a reamer causes small imperfections in this section. These marks were made by varying degrees of wear and tear on the reamer. The main reason why the reamer makes these unwanted marks is the difference in depth between the grooves of the barrel and the bore at the throat.

These marks are perpendicular to the trajectory of bullets. They look a bit like burrs, identical to those found on the opposite side of a sheet of steel pierced by a metal drill bit. When the first bullets pass through the throat, before entering the barrel, the burrs at the end of the throat gently slice the copper surface of the bullets (much like a plane), creating fine copper dust. This fine copper dust forms what looks like plasma when exposed to a high temperature and very high pressure (these are created by the combustion of the powder). This superheated copper vapour is then propelled into the barrel and settles in the form of a thin layer of copper that will stick to the inner lining of the barrel.

This fine addition to the barrel wall will have the effect of increasing the accumulation of copper in the barrel, leading to irregular resistance during the passage of a bullet into the barrel during a shot. This will create variability during a shot, because contrary to popular belief, copper never settles uniformly in a barrel.

Note that this thin layer of copper is not visible to the naked eye unless using a borescope. Moreover, it will be hard to remove once it has settled because it will fuse with the internal surface of the barrel.

That is why it is always preferable to break-in your barrel: To prevent the appearance of this undesirable thin layer of copper in your barrel, until the burrs in the throat are completely removed by the abrasion created during the passage of the bullets.

How do we do that?

There are as many break-in procedures as there are shooters, but the important thing is to regularly eliminate the molten copper deposit that appears during the first shots.

Before you start, here are some important elements:
- It is important to do this procedure before using your rifle.
- It is only necessary to do this procedure once in the lifetime of your barrel.
- The ammunition used must have a copper-lined bullet, free of chemical treatment.
- It is important to use a bore guide to guide your cleaning rod.
- It is important to use a single-piece rigid cleaning rod.

Details of the procedure

1. Clean the barrel of your rifle with a good solvent that can remove the copper.
2. Fire a bullet and perform a complete clean-up.
3. Repeat step 2 four more times. (For a total of 5 bullets and 5 clean-ups.)
4. Fire 3 bullets and perform a complete cleaning.
5. Repeat step 4 three more times. (For a total of 15 bullets and 5 clean-ups.)

Afterwards, we recommend that you clean your rifle after each shooting and never exceed 60 shots between each cleaning.