bobgengeskahn said:
Although I do peak in once in a while to see how that new sniper sub forum is going
There are some major threads all about inner barrels, bbs and hop-ups that IMO need to be moved to that sub forum. Part of the issue is that they do not really see airsoft replicas made for sniping as being fundamentally different from any other replica; the focus being more on producing a consistent output rather than enormous volumes of output (high RoF) for instance.
[quoteI would theorize that in an accurate, smooth barrel, the BB has 'separated' from the top of the barrel by the end, while retaining back spin and is pushed out by the remaining expanding air in the barrel...[/quote]
By the time the BB reaches the 'sweet spot' in the barrel length it should, ideally, be centered in the barrel again due to the surrounding pressure and back spin reaching an 'equilibrium' so to say.
Would you mind explaining this in a bit more detail? I'm not saying you're wrong, but I'm having trouble understanding why this would occur in the first place, and why only at the end of the barrel.
On airsoft I would argue that it is more important due to the simple fact that the air pushing the BB, the back spin and the consistency (or lack there of) of the escaping gas when the BB exits is the only thing we have going for us. So to think of barrels like the Falcon barrel as a really complex crowning, it starts to make sense.
I agree with you here. The crown is indeed very important because it determines both the exit vector and the air-flow around the bb as it exits the muzzle. I never really thought of a Falcon barrel as a long crown, but I do see how it would make an impact there. Perhaps having a custom barrel maker like Edgi make a barrel with the end of it grooved similarly would make for a some good testing.
BeckLR1 said:
Why do some shots go dead center and some fly off to the right or left 12 inches I wonder? Answer that and you can solve "the" problem. If it was as simple as air cushion there would be no random fliers. Ever. It would all ways be consistent every time for everybody and there would only be one size barrel as everyone would figure out what really works in terms if bb to barrel size. Beyond that there is only anecdotal evidence which is at best corollary in nature that barrel size is the key to anything other than creating confusion.
I understand what you're saying, but I actually think that those "flier" shots are explainable, in this case not by the barrel but rather by play in the hop-up system. The reason I say this is that when I have gotten those way-off shots the always seemed to sort of "spin off" to the side after traveling along a relatively straight vector toward the target. It wasn't so much a straight path in the wrong direction. The other reason I say this is because when faced with this further hop-up tuning and tightening always seemed to greatly reduce the amount of these "flier" shots, and the degree to which they are off, or seemingly eliminate them altogether.
That would be me and I did not use clear barrels I used a PDI 6.01 330mm and an Edgi 500mm barrel with .32 Bioval bb's with black dots imparted with a sharpie to see what spin is happening on the BB when it exits.
That's very interesting actually, but it was not this test I was referring to. I am referring to one that ASM's Hunterseeker5 has referred to, and he has in multiple occasions specifically stated that the barrels were clear and acrylic in this particular test. The purpose of the test was not to determine the bb's spin but rather it's behavior inside the barrel. I said "supposedly" because I, nor anyone else I know of, has seen this footage. And Hunterseeker5, in his usual vagueness, refuses to say where to find these test results, or who did them, supposedly at the person who ran the test's request. Honestly, if this were coming from anyone else, I would probably dismiss it altogether. But I am
tentatively willing to believe this simply because Hunterseeker5 has been a highly informative and contributing member of ASM, and has done a heck of a lot of testing and R&D of his own.
I also recall that a Canadian bb company called BBBastard was planning to run some tests of their own using clear barrels and high-speed cameras. Whether they have actually done this I do not know, but I can tell you no results were ever published.
The question is why is the spin different between different shots? And it is not the .3 the thickness of a sheet of printer paper variance between bb's nor is it the air cushion not is it the imperfection in the barrel for if it were it would always cause the same effect which we all know is not the case.
This I would also explain not as a barrel issue but rather a hop-up issue. Contact with anything will produce off-axis spin, but compared to the sheer magnitude of the spin applied by the hop-up the rest are incredibly small. That's why you practically need a bench test to see the difference between a 6.01 and 6.03 of the same brand, and even then you have to be using really good ammo (ie Bioval or SGMs, with SGM's probably being a more relevant test considering Biovals are made with a smaller diameter to be used in 6.01s). Hop-up spin is never a constant between shots unfortunately. We can get closer and closer with tuning, but regardless, assuming all components, the hop-up setup, the barrel, and the bbs, are of good quality, the barrel would logically produce the least variation. Whether the bbs or hop-up produce more variation is largely dependent on the user's ability to eliminate as much play as practically possible from the hop-up setup.
It does not any more than simply using a smaller bb with a tighter barrel would be the exact same as a bigger barrel and a bigger bb.
I agree. This goes back to my earlier comment about Bioval bbs, having a smaller diameter, which I believe is no accident. Bioval bbs seem to preform quite well in the tighter 6.01s.
I measured bb variation between brands 4x bigger than the .02 difference between 6.01 and 6.03.
Yet another source of play. And why it is really not a matter of just using a wider barrel, but rather using bbs and barrels whose diameters work well with each other.
The very process of injection molding bbs is a source of play, especially with the heavy rounds that snipers like to use, simply due to the inconsistent nature of injection molding using high-density polystyrene.
The fact that there are so many variables, and that hop-up and bbs are essentially impossible to hold constant, there may never be enough "clean" test results to say for certain what exactly is happening and why. It is all speculation to some degree.
I wish you luck you your new design and subsequent testing.
Again, I don't claim to know all the answers either, and I think this discussion is great.