Maybe someone knows, are crowns for protecting the barrel , I'm aware that a messed up crown affects accuracy and a lot of accurate guns have no crown, with so many guns with suppressors now days crowns are unnecessary right ?
Crown or no crown
- Thread starter Rawroots
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The crown is the release point of the barrel. The crown IS on ALL barrels. How good the crown is finished can affect accuracy, might even say will. So your last question is moot.
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Crowns simply are the (sometimes but not always polished) end of the barrel. They are not a protective device, like a muzzle brake could be.
I am frankly confused by the contradictory things I hear about crowns and accuracy. Some swear by a perfectly cut crown for accuracy. They get close to a state of panic when the barrel lands & grooves do not end perfectly even, cut in a lathe. But most of my barrels are far from such perfection yet are very accurate.
One guy even experimented by chopping off barrels in an angle with a grinder, yet accuracy remained reasonable.
I am taking away from this that I like a clean barrel with a clean looking crown, which I typically polish with very fine grain (1000) sandpaper, wet with silicone oil. Avoid damaging the crown but don't strive for crown perfection either. PCP accuracy is the result of several factors. Remove gunk from a new barrel and try out pellets it likes. Avoid clipping pellets in a badly aligned silencer. Be wary of POI shift due to a defective or poorly attached scope. In a more advanced stage, tune hammer spring, regulator setpoint (if gun is regged), and maybe valve spring tension.
I am frankly confused by the contradictory things I hear about crowns and accuracy. Some swear by a perfectly cut crown for accuracy. They get close to a state of panic when the barrel lands & grooves do not end perfectly even, cut in a lathe. But most of my barrels are far from such perfection yet are very accurate.
One guy even experimented by chopping off barrels in an angle with a grinder, yet accuracy remained reasonable.
I am taking away from this that I like a clean barrel with a clean looking crown, which I typically polish with very fine grain (1000) sandpaper, wet with silicone oil. Avoid damaging the crown but don't strive for crown perfection either. PCP accuracy is the result of several factors. Remove gunk from a new barrel and try out pellets it likes. Avoid clipping pellets in a badly aligned silencer. Be wary of POI shift due to a defective or poorly attached scope. In a more advanced stage, tune hammer spring, regulator setpoint (if gun is regged), and maybe valve spring tension.
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Crown is the exact point the projectile leave the barrel, is the crown is uneven then the air will exit the barrel unevenly which could and usually will affect accuracy especially down range.
https://youtu.be/9MOlxPdnbww
https://youtu.be/9MOlxPdnbww
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Sometimes a barrel will group well despite a gnarly looking crown but I’ve seen numerous examples where dressing a factory crown has noticeably improved precision, and in some cases completely transformed a poor performer. Crosman and SPA (Diana) are some repeat offenders I’ve run across.
Regarding cutting the crown in a lathe, that is a good way to ensure the facing cut is nice and straight but even a very sharp cutter will tend to smear a bit of metal so it’s a good idea to do the final step with a fine abrasive to remove any burrs. This example was done that way…faced in a lathe, then a brass screw with fine compound to establish the bevel. I do that step with a handheld drill and move it about in an orbiting motion to avoid creating an irregular bevel. Notice the well-defined rifling profile visible under magnification.
Regarding cutting the crown in a lathe, that is a good way to ensure the facing cut is nice and straight but even a very sharp cutter will tend to smear a bit of metal so it’s a good idea to do the final step with a fine abrasive to remove any burrs. This example was done that way…faced in a lathe, then a brass screw with fine compound to establish the bevel. I do that step with a handheld drill and move it about in an orbiting motion to avoid creating an irregular bevel. Notice the well-defined rifling profile visible under magnification.
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A properly machined crown is important, and its been proven absolutely true. But like most things barrel related, it is somewhat specific. I've seen a few ugly crowns shoot well, but that's the exception. I favor a recessed crown, where a bit of protection is afforded by the outer surface.
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