Quote:
Originally Posted by ThunderCactus
They float. If they rolled along the top, there would be a clearly visible line along the top of a very dirty barrel. And there never is. Keep in mind chamber pressures in shorter barrels are often in the 60-120psi range as well, that's a lot of centering force. AND the magnus effect gains effect only as the BB slows down and gains more "grip" on the air. During the first 10-20ft there's almost no magnus effect at all. Otherwise the BB would start lifting immediately upon leaving the barrel, instead of 60ft into it's flight path. It's a very gradually increasing force over distance and deceleration (of forward velocity and backspin), not a constant effect.
The bore has never seemed to make any particular difference.
I've seen everything from a 6.01 to a 6.23 under ideal conditions and honestly never found one that works noticeably better than the other.
Physics is physics, but science works by applying theories to field proven fact. Not trying to DISprove field proven facts with theories.
Same is said for barrel length, haven't seen any really solid evidence for longer barrels being more accurate than short barrels. The hopup is a far greater contributing factor, making comparisons more difficult. But there hasn't been any real correlation between length & accuracy, or you'd see short barreled guns like pistols, P90s, TW5s, 9" cqbr ptws and the like consistently get worse groupings than M4A1s, M16s, 24" sniper rifles and the like.
The fact remains, once the BB has been stabilized in a straight flight path, no extra amount of barrel will ever make it any more stable. And higher pressures seem to stabilize the BB in shorter distances.
Bore quality; consistency and circularity, are still the most important factors.
Accuracy will degrade as the barrel fouls and the one thing i HAVE found is that wide bores and short barrels tend to foul less quickly.
6.03-6.08 is still the ideal range. The downside to going to a 6.13 or 6.23 is the incredible amount of air loss around the BB, requiring more air volume for not a lot of gains. The PDI 6.05 is my go-to for rifles, 6.13s for LMGs.
6.00 & 6.01 are specifically for exploiting higher fps, not for accuracy.
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I agree with everything except for the statement that the BBs float.
If you head on over to ASM, you'll be able to read up on the details.
Somebody took high speed footage of a BB traveling through a transparent barrel. The resulting footage definitively proved that the BB initially bounces around immediately after being hopped, but then eventually travels along the top of the barrel until it exits.
Unfortunately, this video was removed from the public view soon after being posted.
BBBastard attempted to replicate this same test in their Real Time Airsoft Barrel Dynamics kickstarter campaign. However, it never received enough funding.
http://airsoftcanada.com/showthread.php?t=145636
Numerous other tests involving coated BBs and then milling off parts of the barrel revealed similar results.
Based on this, we can comfortably assume that the BB does ride along the top of the barrel.
We can explain the better long range performance of widebores by assuming that a larger bore means less surface contact of the BB with the barrel. This means less friction and thus less change in the angular momentum of the BB as it leaves the barrel. Additionally, the large bore and air volume provided by HPA systems will likely stabilize the BB from its bouncing stage in a shorter time and thus shorter distance as compared to a tightbore barrel.