The truth about rifle barrel crowns

As part of an ongoing series on what to look for in a custom rifle, gunsmith John Stewart tells us all a little more about the barrel crown.

John Stewart of Kiote Corp writes: Everyone knows a barrel should be crowned. But not everyone pays attention to what kind of crown should be used, or how deep it should be, or in some cases, when a crown is contraindicated.

For 90 percent of my applications, I use a 10 degree Cooper Crowning tool. I only recess the crown by 0.100”. I find that this type of crown serves most of the practical and hunting shooters, affording more than adequate protection to the muzzle should it be dropped or banged up.

It provides a concentric and parallel bearing surface to the muzzle ensuring proper alignment and interaction with the projectile. It also ensures that the lands are cut parallel with the muzzle and ensures that there is an even bearing surface on the projectile as it leaves the barrel. A properly cut crown, on a quality barrel, should show the clean cut lands of the rifling at the muzzle.

There is no real technical reason for why I only cut it back by 0.100″. I’ve found that in the cases where the consumer uses a muzzle brake and/or suppressor, this depth allows easier cleaning of the muzzle than a deeper cut crown.

I find that almost no one thinks about cleaning the muzzle/crown of their barrel. Especially in the case of brakes and/or suppressors. The blow back that accumulates on the crown doesn’t take long before it quickly and severely affects accuracy.

And when those people do clean it (only after my prompting and sometimes scolding), they use sharp objects like a knife or razor blade to scrape the fouling off. BAD IDEA! While you’ll probably not gouging the surface, you are etching it and literally destroying the crown in microscopic ways. It takes longer but it never hurts the barrel to use a bronze brush and a little elbow grease.

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34 COMMENTS

  1. “or in some cases, when a crown is contraindicated”

    And those cases are….?

    The editor should have sent this back to JWT, and he should have sent this back to John Stewart, to finish this article. All I see as far as a crown goes is “I do this”, “clean it”, and (what to look for in a custom rifle – the barrel crown) “you should be able to see the lands.”

    It is like a partially formed idea, but I’m certain that John Stewart has a fully formed mental picture of what to look for, and avoid, WRT the barrel crown on a custom rifle job.

    • I kept scrolling down, thinking there must be a “page 2” link or something… it’s like they forgot most of the article! A few generalized opinions, then… nothing!

  2. Doesn’t the size of the crown depend upon the ‘profile’ of the barrel, and the size of the barrel at the muzzle? Can’t cut whatcha don’t have. If we’re talking only of crowns, I was thinking it would be about in some sort of ratios relative to the O.D. of the barrel, or at least I.D. of the bore? Ehr Dern’t Gknere.

    That’s a big HB, in the OP, for not being a test barrel. What the fudge is the caliber (chambering), and how accurate is it in MOA? Is it a lot more accurate with the crowning work, or ~ some. How much does it cost (approx.)? Do Ohole’s new rules apply.

    • Not a dumb question, the article should have been more clear. In the first picture, the recessed area around the muzzle end of the bore is the crown.

      It’s important because as the expanding gases propel the bullet out of the barrel, the muzzle is where the barrel stops being in control of the bullet’s path. If that ‘last mile’ of rifling is damaged or imperfect the gases will come out asymmetrically and push the bullet in an unwanted direction.

    • The crown is the junction where the bore meets the front face of the barrel; it is the very frontmost “corner” of the bore that determines whether all parts of the bullet have gas escaping equally around the base of the bullet as the bullet leaves the bore.

      If the crown is off, or the crown has a burr or damage on one side, the bullet gets upset (gyroscopically upset, not emotionally upset) as it is leaving the bore, which can often result in larger groups downrange.

  4. There are perhaps a half-dozen styles of crowns in common use, depending on the age, manufacture, type of gun, etc.

    For many modern rifles, the recessed “target crown” (which is what we see above) is popular. When we look back in time, rounded crowns were more popular (ie, the face of the muzzle was more rounded, or conical, blending to a rounded outer area). Some crowns are cut to 11 degrees off normal. Go look at a rack of rifles in a gun shop with lots of older, used rifles and you’ll see what I mean. There’s at least a half-dozen styles of crowns out there in the last 100 years or so.

    How to cut crowns: I do mine in a lathe, but they needn’t be, if you’re willing to part with some cash to buy the correct type of piloted tool that uses a pilot that goes down the bore. Both Dave Kiff and Dave Manson (of PTG and Manson Reamers, respectively) sell piloted crown-cutting tools. The barrel should be held in a vise, vertically, and the tool carefully inserted into the bore, lubricated with some cutting oil, and spun as evenly as possible. Do a little, then carefully remove the tool, clean out any chips/swarf, clean the bore of any chips/swarf before re-inserting the tool, continue until you have the muzzle cut as you want.

    If you’re cutting crowns in a lathe, I use an indicator rod (from one of the Dave’s shops, previously mentioned) to indicate the barrel’s bore to be running true on the center axis of the lathe spindle. I use a test indicator for this job, and I have the barrel or the barreled action inside the spindle, and I have a spider on the outboard end of the spindle to adjust the coaxial indication along the indicator’s length. Do not indicate from the outside profile of the barrel, especially on modern factory rifles; I’ve seen recent production Remington 700’s where the outside barrel contour had 0.018″ of runout from the center of the bore. That’s absurd, but that’s modern gun production for you.

    Indicate off an indicator rod in the bore, pull the rod, and then get a 1/4″ HSS tool blank. Sharpen it into a LH finishing tool, with a point you can get into the bore without binding on the bottom, or touching the point to the other side. Sharpen the cutting edge until you can shave hair off your knuckle with it – this will need to be done on a fine grit hand stone when you get the rough profile ground on with a grinding wheel.

    When you cut the part of the crown where the bore transitions into the muzzle face, this should be a clean, crisp edge. To check for burrs, get a cotton Q-tip, pull at the cotton on the end to “fluff” the Q-tip out, then put the Q-tip into the bore, spin it, and pull it back out slowly. You should not have any fibers dragging on a burr where you cut that edge. Finish the face of the muzzle outwards as desired. The ability to cut that inside bore-to-muzzle corner without leaving any burr whatever is the reason why the tool needs to be exceedingly sharp.

    • Dyseptic Gunsmith,

      Thank you so much for your comment here. I have an inexpensive break-action rifle in .44 Magnum that seems incapable of shooting anything better than 2-inch groups at 25 yards. My guess is that the crown sucks and I was hoping to crown it myself — but I don’t have a lathe. I will be looking to purchase a cutting tool at the sources that you indicated.

      • I have used and would recommend the Manson tool, but if you’re only doing one barrel it’s cheaper to pay a smith to do it. If you decide to crown it yourself go slow, you’ve got all the time in the world to screw it up so why rush.

      • It could be the crown, it could be that the barrel has other faults. It’s difficult to tell these things without seeing the firearm “in person” so to speak. It’s impossible for me to say whether re-crowning that rifle would improve your situation without looking at the rifle, the current crown, the rest of the bore, etc.

    • This should have been the article. Much more informative than just saying a crown is important and remember to keep it clean. Thanks for taking the time to make this comment.

        • If I ever do video in a gunsmithing shop, I’ll have some ladies who are wearing tiaras, and are dressed in high-class evening gowns as my assistants. They’ll have the very best in fashionable eye protection for my shop, and I will work with Manolo Blahnik to create a line of fashionable safety shoes for women.

          If I can’t do that, then I see no point of video…

    • This reply is 100% more informative than that sorry excuse for an article. Stop letting drunk people post articles on TTAG!

    • I always love reading your comments. I tend to think I know quite a bit about firearms (and I do, even compared to probably 90% of gun owners), but damn near every time I see something from you, I realize how much more there is to learn. Valuable and humbling.

      • Anyone, and I mean anyone, who tells you that they know everything about guns is simply full of crap. Period, end of discussion, no one needs to debate this issue.

        Every week, I learn something more/new/interesting about guns. Every single week. There are days when all I can think is “Cripes, I feel stupider than the day before…” mostly because I’ve just discovered a whole new area of firearms research to be done that I had no idea existed only yesterday.

  5. Interesting post on the mechanics of cutting a crown, but I have to agree with Eric and Red. Need more input on the what, where, why’s, how is covered.

    • Specifically, I’mna looking for a rifle for purpose ‘X’. I see a rifle on a rack and pull it out and see the crown…? Assuming it’s otherwise acceptable for purpose ‘X’, is there a NOGO based on the crown?

      • When I’m evaluating a rifle needs re-crowning, the “do it” decision is usually because there is obvious damage to the crown/muzzle area that I can see with a set of +2 specs or my Optivisor hood, or it drags a q-tip, or I cannot fit a gage pin for the bore diameter (lands) down the barrel (because the crown is distorted). ie, there’s something I can see or measure that is wrong with the crown.

        Other reasons why a customer might want a crown re-cut is because they don’t like the appearance of the existing crown, or it has a bunch of dings/scratches/etc on the outside edge of the crown, etc.

        • I always love reading your responses. I tend to think I know quite a bit about firearms (and I do, even compared to probably 90% of gun owners), but damn near every time I see something from you, I realize how much more there is to learn. Valuable and humbling.

  6. JWT, is do you happen to know if this is the same John Stewart who taught the Design and Function course at the Colorado School of Trades? I can’t imagine there are that many working gunsmiths out there by that name.

  7. My rifle smith will ask me on a rebarrel or new build what crown I want and I always say, the most accurate one.

    • In my shop, I do most all crowns in the lathe, and my charge is $125, more or less, depending on how easy it is to get the barrel into the spindle.

      Other ‘smiths who re-cut a crown with a piloted tool might charge only $40 to $50 for a re-crown job.

  9. At our club we have used every type of crown out there and found none superior over the other including having no crown at all as Winchester at one time used to do. As long as the crown is done properly there is no difference in accuracy period. This may not be true if you use silencers but I have no experience with this and even if true how long would it take to screw off a silencer and clean the crown?

    • I agree – I’ve not seen any accuracy/precision differences between any of the various cosmetic treatments of a crown, other than perhaps cleaning issues. There are aesthetic differences and “I wouldn’t do that’s” – eg, I wouldn’t put a recessed target crown onto a fine, high-end game rifle. It would look “wrong.” It would function just fine, it would just look wrong.

      Likewise, an old-style Winchester crown on a modern target rifle would look…. “off.” Since I spend a fair bit of time worrying about cosmetic issues on my customers’ guns, choosing a crown that looks consistent with the pattern of the gun is part of what I do on a crown.

      The thing I seek most out of a crown is protection of that edge between the end of the bore and the muzzle. As long as that edge isn’t broken down, damaged, dented, etc if the muzzle contacts the floor/ground/etc, I think the crown, however it might be fashioned, has done its job.

  10. Thanks for the tip about how muzzle alignment is also an important thing to consider when planning to get custom rifles. I’d like to start collecting guns soon because I’m interested in learning more about weaponry. Owning some myself would be a nice idea.

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