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Originally Posted by Scarecrow
Stalker, you seem to have you shit wired well on ballistics...
I've always assumed that tightbore barrels with a weighted BB (.25 or better) wouldn't necessarily give you a significant distance advantage, but would give you more of a tighter grouping on the target. Am I right or wrong on this? I base this on observing that my M16A4 with the Prometheus TB and .25 BB Bastards, I get terrific distance and grouping at the target - less so with my C8 which also has a chopped down tightbore, but stops about 15ft short of the M16A4 with a wider grouping. .20 goes very wide and much shorter than the .25
BTW, I've used that walk-in trick as well (poor Titan, he was stunned) and it never fails to amaze someone when you hit them at an insane distance, but its really just an old pballer lobbing trick that I always feel sheepish about using afterwards.
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Blame it on my constant tinkering and experimenting with sniper rifles, trying to get the best range and accuracy. My GBB work was pretty much the fact one training day with team mates using pistols only, I couldn't hit a team mate 40ft away with my G19 using 0.25g BBs, call it a bit over hop on them, so I swore never again unless I needed (as in reloading GBB mags in the field from my AEG mags.) Since I had quite a selection of BBs to try out from my sniper ammo collection, I tried 0.36g one day and was stunned I could dump rounds on a 55 gallon drum (lying prone) 120ft away, and since then been studying GBB ballistics with heavier ammo.
Only thing that heavier BBs will give you for range is greater stability. Meaning, hop up will keep the BBs on course for longer, will be more resistant to air currents it passes through (takes more air density, aka. eddies, light winds, etc.) making it more accurate at longer ranges. Case in point, a lighter BB will be more susceptable to fly off course sooner. One thing that isn't mentioned about the benefits of hop up (only that it creates lift and helps BBs fly farther) is that hop up also decreases drag. If the BB isn't spinning while flying, the boudary layers or airflow around it's surface separates near the rear of the BB, causing vorticies to occur which basically acts as suction. Spin the BB, airflow around the BB will be smoother with a greatly reduced amount of drag, and will create higher pressure on the bottom front thhan the top, giving the lift. Heavier BBs require more hop up, which would, in my mind, increase the rate of spin on the BB. Make the fps higher, the faster the spin on the BBs, therefore a reduction in hop up is needed to keep it stable. Keep in mind this is just me thinking, I don't have windtunnel tests to prove it (but hey, I DO have access to windtunnels through work, wouldn't THAT be an amazing thread of information?!!) So nutshell is, there is a threshold in fps that makes 0.20g BBs more attractive to use, but really only in controlled environments (I wouldn't hesitate to use 0.20g indoords with short distances).
On thing that I've been saying for a while, in regards to lighter/faster BBs vs heavier/slower BBs is there are two different types of "range", and a lot of people tend to focus on the first, that lighter will go faster and travel farther. Look at it this way, there is range = where the BBs lands vs. range = effective range to hit man-sized targets. I focus on the latter, some only really only think of the first one and just accept it's poor performance at longer ranges as being part of the airsoft experience.
Here's a great thread that got very interesting after a while regarding airsoft ballistics.
http://warmongers.dyndns.org/forums/viewtopic.php?t=569
I've also written some stickies of info for people, one includes trying to expalin airsoft ballistics to team mates and other interested parties.
http://warmongers.dyndns.org/forums/viewforum.php?f=31
Hey, can any of you that are smarter that I am in mathematics figure out a formula to find what rate of spin certain amounts of hop up at certain velocities would be? I've always been curious the rate at which a BB spins. If I can sort that out, I might be able to get some contacts to borrow some windtunnel time to get some footage of airflow around spinning balls.