sniperelite7 Posted January 21, 2012 Report Share Posted January 21, 2012 How important is it? I recently bought a new madbull 6.03 barrel to replace my current barrel which I had modified, and had affected accuracy. Needless to say the new madbull had arrived and I noticed that the crown had some damage right on the rim. The surface had appeared to be scratched in some places, bare aluminum showing. Granted the defects where small, no actual deformation of the crown, just what amounted to a few rough patches on the crown. However I couldn't help but feel unease, i've been trying different hopup configurations for my p* fusion dmr in an effort to get the hopup/barrel combo to an exceptional level of accuracy and this did not bode well. So I started searching for ways to repair the damage, but also to see just how much accuracy would be effected. Planning on testing when daylight hits tomorrow. During this searching I stumbled upon this article http://airgun-academy.pyramydair.com/blog/2011/09/the-importance-of-the-crown/ Interesting? Now I realize BB, pellet, and bullet dynamics are going to be way different from each other. But certain principles do cross over, and the importance of a good barrel crown has always been preached in the airsoft community, at least in the forums I tend to browse. Yet, one can't help but notice that crowns seem to vary between each manufacturer, you'd think that as much time as we spend on finding the optimal hopup setup that we would place as much emphasis on the most optimal barrel crown, but we don't. Maybe the barrel crown doesn't matter at all, so long as it is not physically interacting with the bb's like the bore of the barrel is. Or maybe i'm just trying to comfort myself in light of the potentiality that i've blown forty dollars on a worthless barrel. Link to post Share on other sites
teflon don Posted January 21, 2012 Report Share Posted January 21, 2012 it doesn't really matter there are so much other variables that you won't notice the difference of the crown but you could recrown it Link to post Share on other sites
Bane Posted January 21, 2012 Report Share Posted January 21, 2012 I've done *LOTS* of crowns on rifles real and airsoft. The only important notes are thus. Crown is *EVEN* (Aka, not on a horrible slanty angle) Crown does not have any BURRS on the inside (Basically polishing compound or similar Crown (In terms of airsoft) is not dinged on the *INSIDE SURFACE* of the barrel, AKA where the beeb can hit a high spot on exiting Otherwise, it makes no difference. Link to post Share on other sites
farrasdevell Posted January 21, 2012 Report Share Posted January 21, 2012 Does this carry to the porting of inner barrels? I'd always assumed the idea behind crowning was to smooth the exit path of gasses/pressurised air behind the bb minimising turbulence. All be it minimally and a fairy null point with a correctly matched cylinder ratio. Thoughts? Link to post Share on other sites
sniperelite7 Posted January 23, 2012 Author Report Share Posted January 23, 2012 I always thought porting was a fairly useless concept. If, as you said, the gun has a properly matched cylinder ratio, the air should not effect anything. On that note, it appears the damage to the crown has not affected accuracy as my gun was printing 3-5 inch groupings at 100ft, bearing in mind the wind was being quite random today. Was also able to score consistent shots on a piece of 8.5x11 inch piece of printer paper at 200ft. Link to post Share on other sites
hwagan Posted January 23, 2012 Report Share Posted January 23, 2012 I cut down barrels with a hacksaw, and crown them with the pointy end of my K-bar. Both inner barrels for my WOC have had that treatment, and there's no noticeable change in accuracy. Might be a different story in a high FPS sniping setup, but it doesn't seem to make a difference at 350FPS odd.. Link to post Share on other sites
demoncase Posted January 23, 2012 Report Share Posted January 23, 2012 I cut down barrels with a hacksaw, and crown them with the pointy end of my K-bar. Both inner barrels for my WOC have had that treatment, and there's no noticeable change in accuracy. Might be a different story in a high FPS sniping setup, but it doesn't seem to make a difference at 350FPS odd.. Agreed- cut 'em down and make sure the end of the barrel is perpendicular to the tube, the nice even deburr/crown with a sharp object.... 10 years of modding barrels this way between 250 and 500fps, on AEGs, GBBs and Springers with no ill effects felt on target. In truth, for the amount of 'gas' (or air in most cases) behind the BB, I doubt there will be enough effect upon the sub-1 gramme ammo we use to be measurable if we used different crown angles....If you've got all the burrs off then anything else is a frippery. When you are talking the amount of hot gas behind a real rifle round, this is a different matter- A well selected crown helps stabilise the round and vent gas correctly. Link to post Share on other sites
Rayh Posted August 7, 2012 Report Share Posted August 7, 2012 I am not sure if it makes much difference with the low velocity and "loose" tolerances in airsoft barrels but it is vital in centrefire rifles. I have recrowned all my hunting rifles at different times, ranging from .22s to .243 and .308 centrefires Its hugely important for accuracy,the main points being, as previously quoted, that the crown is flat at the end of the barrel and if done properly should have a slight inward chamfer, eliminating any rough edges I have usually done the job with a brass round bit. In a pinch a large round headed brass screw will do the job Link to post Share on other sites
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