Gas Gun Barrel Break-In

Easier cleaning and potential accuracy enhancement for the life of precision AR-15 barrels.

by Joe Carlos

In a former life I spent 28 years as a full time Pennsylvania Game Warden. In tracking down poachers and solving various game law infractions I often asked the same questions as any other law enforcement officer: Who, What, When, Where, and How? Let’s use that approach with regard to the topic of gas gun barrel break-ins.


We gunsmiths can either do the break-in ourselves or leave it for the customer. Most of us in the profession are busy, real busy! While we probably don’t want to add such tedious tasks to our already full plates, we are the professionals and have many tools that shooters don’t have or need. One such tool that is helpful to properly breaking in a gas gun barrel is the bore scope. As professionals we have a greater understanding of how easily damaged the bores of our firearms are, especially if they are made of stainless metal. This extra knowledge and care, coupled with tools to observe and avoid unintended damage, makes our firearms better.

There is another, somewhat selfish reason for the gunsmith to break-in the barrel. Regarding the Bay of Pigs, JFK noted, “….victory has 100 fathers and defeat is an orphan.” Would any of us want to see a real tack driver leave our shop only to come back a few days later ruined by an improper break-in? I have seen it happen! Who is that gun owner going to blame? One of two “orphans” being either the barrel maker or the gunsmith who installed it. He will not blame himself and, in his defense, damaging a barrel via improper cleaning is easy to do yet hard to detect that he probably won’t even know he was at fault. So, at the very least, if we don’t tackle the job we owe it to our customers to inform them of the proper tools and techniques to do the job right.


What are the goals of a proper barrel break-in? To burnish the pores of the metal forming a smooth surface less prone to snag at the bullet. Smoothing out any angular tool marks left as a result of the chambering process. Removing any burrs at the gas port caused by the drilling process. “Above all else, do no harm” to the barrel while achieving the first three goals. That misquote is often attributed as part of the Hippocratic Oath. While it was said by Hippocrates, circa 460 BCE, it was not a part of the oath itself. Nearly twenty five centuries later, I think that in our jobs as gunsmiths it is still a very good work ethic to embrace.


The very term “break-in” alludes to the answer to this question. A break-in needs to be done starting with the first shot through the barrel. Even a few shots before beginning the process will exacerbate the frustrations, time, effort and danger of doing harm to the barrel. If you are a gunsmith who doesn’t elect to do the whole break-in process but likes to function fire the gun (a good idea) please bear this in mind.

Read more in our October 2014 issue. Back issues are available.

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