All About Rifle Muzzles and Crowns
The recessed target crown. The 11-degree target crown. Sounds exotic. Sounds accurate. Sounds special.
That's what gun makers want you to think.
While the ads make various muzzle crowns sound like the latest high-tech accuracy feature, they really aren't. An 11-degree target crown won't necessarily make your rifle any more accurate than a 9-degree crown, 13-degree crown, rounded crown, or flat crown. And a rifle with a recessed crown isn't going to save the day. But it might.
A recessed crown means the muzzle, the absolute end of the bore, is cut back from the absolute end of the barrel. This leaves a rim or protruding edge of barrel steel jutting a bit past the hole of the muzzle itself. This provides a modicum of protection to this critical area, and here's how:
A rifle's muzzle, that final edge of the rifled bore, can enhance or degrade a bullet's accuracy. If the edge is perfectly even and concentric, it creates a precise release of superheated gases that jet around all sides of a bullet evenly. But if the edge is dinged, scratched or grooved so that gases jet from it before or behind the other gases, the bullet can be disturbed or nudged off course.
A muzzle that is recessed is less likely to be gouged by contact with foreign substances. What substances? Rocks. Gravel. Believe it or not, some hunters have been known to travel with their rifles resting muzzle down on the floorboards of vehicles! That's a great way to grind gravel into the critical edge of a muzzle and damage the rifling lands or grooves.
Other gun owners have been known to vigorously clean their barrels by ramming a rod gleefully and repeatedly down the muzzle. If these rods are too hard or so soft (aluminum) that they hold grit, they, too, can damage the inside edge of the crown/muzzle junction. This is why you are advised to clean rifled barrels from the breech.
OK, fair enough, but what about this 11-degree target crown business? Over the years I've found no definitive answer for that. Some gun makers say it's the best angle for boat tail bullets. Others say that's a myth. Regardless, it's probably overkill to your average hunter, plinker or even long-range varmint shooter who can't begin to realize or appreciate the subtle, if any, change in accuracy from one crown shape over another. In short, don't sweat it.
However, if you have a damaged crown/muzzle edge or think you might your rifle's accuracy could suffer noticeably. Check for this by carefully studying that edge with a magnifying glass. See any obvious dings or deep gouges? Check the concentricity of powder residue at the muzzle, too. Is it a nice, even ring, or lopsided? Another trick is to pull a Q-Tip across the muzzle edge to see if the fine cotton fibers catch on any burrs or rough spots. If you find or suspect damage, a gunsmith can repair it easily with a bit of honing or re-crowning. If you're brave you can do the job yourself. Gunsmithing supply stores sell hand crowning cutters for around $50 and brass muzzle crowning laps for touching up muzzles at around $15 each.
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