If you’ve been a reader of AccuracyTech I’m sure you’ve heard me joke about barrel break in at some point, just shoot the snot out of it! While that’s true I think it’s time to delve a little deeper into the issue of barrel break in. This is another one of those topics with a lot of lore and legend surrounding it. Most of it stemming from Benchrest and other disciplines of extreme accuracy and anal levels of procedure. For the tactical shooters, we’re a little less about the size of the group, and more about making the hit on the first or second round, anywhere, any time, any condition. So the procedures for barrel break in are bound to be different, that’s not a knock on other disciplines. Merely, it’s a statement of fact, different objectives have different processes.
Barrel Break In
Just shoot it! This has been the long standing joke in the tactical shooting community. Where many in other disciplines have very anal and rigid guidelines for barrel break in, we don’t. Some suggest fire a round, clean the barrel, fire a round, repeat for the first 50 rounds. To the tactical shooter, I say just shoot the gun for 10 or 20 rounds. Run a couple wet patches through the bore just to ensure you don’t have any excessive amount of copper fouling up the barrel, then shoot the rifle some more! Sounds easy, right?
Well, it is! Just shooting the rifle is going to do a number of things for barrel break in. For starters, you’re fouling the barrel. The barrel will have different points of impact when it is new and clean and when it is fouled. This is why if you do clean the rifle, always put another five rounds or so through it before you put it away. Put it away fouled so you have a consistent point of impact and zero when you pull it out next time. You don’t want to clean the barrel, put it away, and have to deal with the clean bore versus fouled bore shift when you start shooting next time!
Another portion of barrel break in that is relevant, especially to hand loaders, is the issue of the barrel picking up speed. It has been my experience, and that of many other people, across a multitude of barrels and calibers, that most barrels will pick up some speed somewhere in the first 100-200 rounds through the barrel. My experience has been that a new barrel tends to settle in and achieve it’s consistent speed around the 125 round mark. After which any speeding up tends to drop off and before which speed may still be picking up.
Don’t discount this, because it is significant. I shot a match on a new barrel once with around 60-80 through it at the time the match started. During the course of the day the barrel would go on to pick up an additional 200fps over the baseline I had established with a chronograph. I was shooting Copper Creek Ammo at the time and was initially surprised when the first box or two through the gun was coming in a good 200fps under the advertised speed of the ammo from Copper Creek. By the end of the match, I was shooting high on a lot of my shots and scratching my head a bit until I re-chronographed the ammunition. Then I saw the light! By picking up that missing 200fps it had built in a pretty sizeable difference in my DOPE for shots at distance.
The point here is, don’t shoot a match on a new barrel, or you’ll be contending with having your DOPE shift around as the muzzle velocity increases as the barrel finishes breaking in. What’s the cause of this? I think there are a number of factors. Minor imperfections in the bore are smoothed out by the passage of projectiles down the bore under pressure and at high velocity. The fouling of the barrel likely has little to do with speed, but a lot to do with point of impact versus point of aim. I think there’s likely some initial movement in the throat area of a new barrel as the first 100+ round pass through it at high velocity.
After these initial variables settle into their final dimensions, or at least final for the foreseeable future, the speed of the projectiles as they leave the muzzle becomes much more stable and consistent than in that initial 100-200 rounds. I’ve heard that several manufacturers won’t even discuss accuracy or velocity questions with customers until they have a minimum of 200 rounds through the barrel. That would seem to make sense in the context of barrel break in and our discussion here today!
Remember, while the whole, “just shoot it!” method of barrel break in has merit and makes us all laugh, there is a touch more to it than that. Be cognizant of how many rounds you have through the bore and the likelihood of the barrel picking up muzzle velocity. Be especially conscious of this if you plan to hand load ammunition for the barrel. You don’t want to burn expensive bullets just to get through the initial stages of barrel break in. For that I suggest some cheap, factory loaded ammunition in your caliber of choice. Especially if you can re-use the brass and squeeze some additional value out of the factory stuff you’re using to break in your barrel! As always, if you have questions or something to add, please do so below in the comments!