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.