Barrel Break-in

Having been asked several times about barrel break-in, I thought I would go ahead and put together a page dedicated to break-in.

Let me start by saying that I am no expert on the topic by any means. However, what I have read and learned about the subject, it makes sense to utilize some sort of break-in procedure.

One of the quickest ways to prove to yourself that the procedure is needed is to take any piece of machined metal and make it "slick" by way of emery cloth or grinding compound. A perfect example would be to take a look at the anvil portion or top side of the jaws of your bench vise. These surfaces are machined metal. Pot metal, cast iron whatever, the surfaces have been cut with a machine.

Take a piece of emery cloth, under one finger, rub the surface in the same spot for a couple of minutes. Before you know it, the spot is obviously "smoother" than the areas you did not "Polish".

I won't dive into the manufacturing process of barrels but there are many books which discuss it at length. Basically, a solid steel rod is drilled through and then the rifling is either cut or swaged into the hole that becomes the bore.

The drilling process leaves in it's wake, a machined surface. The rifling process does not smooth out the machined surface completely and in fact generates more surface area. Think of a sprocket. Each tooth has 2 edges. Now you have the surface at the bottom of the valley and the surface on the teeth edges. Lands and grooves.

All of these surfaces are machined in one way or another and will have "rough" spots on them. Granted, not nearly as rough as the surface of your bench vise, but rough none the less.

The following procedure is an article by Jim Shults that ran in the April 1998 issue of Petersen's Rifle Shooter.

I wrote to Petersen's and requested permission to reprint the article in January of 2002. They have yet to answer other than to say that the letter was forwarded to home office.

I used this procedure on a new 220 Swift MKII in 1998 and the gun still shoots fantastic groups.

The pages are saved as images and will load slow but be patient, it's worth it.



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Last Modified: Thursday, April 16, 2020 1:52 PM