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Something intresting.
Posted: Tue Jun 21, 2011 10:58 am
by warhead052
I found out today, that a 1/8" brass nipple, is the perfect fit for an airsoft bb. I am using .12g seamless bbs and they fly excellently. I guess I need to get some longer sections of 1/8" pipe for my next project.
Posted: Tue Jun 21, 2011 11:01 am
by POLAND_SPUD
was it a pipe nipple?
Posted: Tue Jun 21, 2011 11:11 am
by warhead052
It was, I stated that. I was amazed that it worked though. It worked pretty well even though it was 2 inchs long.
Posted: Tue Jun 21, 2011 11:19 am
by cammyd32
I just buy cheopo 6mm aluminium tubing for that job.
it works brilliantly.
Posted: Tue Jun 21, 2011 11:20 am
by warhead052
Yeah I dont think my local lowes or home depot has it. If they do then I obviously missed something.
Posted: Tue Jun 21, 2011 1:33 pm
by farmerboy32
check out some online suppliers. I ordered a steel 6.04mm pipe before frome speedymetals i believe
Re: Something intresting.
Posted: Wed Jun 22, 2011 11:05 am
by dewey-1
warhead052 wrote:I found out today, that a 1/8" brass nipple, is the perfect fit for an airsoft bb. I am using .12g seamless bbs and they fly excellently. I guess I need to get some longer sections of 1/8" pipe for my next project.
To comprehend how much "slop" or blowby there is, look at this drawing comparing amount of clearance or blow by.
1/8 Brass Nipple/Pipe vs Airsoft 6,03mm Tight Bore vs Carbon Arrow.
Posted: Wed Jun 22, 2011 11:10 am
by warhead052
Well dewey, since there has to be room for the bb to get sucked into the barrel, its not that bad. Its better than the 3/8" barrel I have now.
Posted: Wed Jun 22, 2011 11:16 am
by jackssmirkingrevenge
Something interesting from the BBMG wiki
even if I say so myself, I wrote:Barrel tightness
The BBs should fit the barrel well enough to minimize leakage of air around the projectile (blowby) but not so tightly that friction is excessive. Even small differences in diameter can have significant effects on performance. An attempt to quantify this power loss was made in this experiment
Two 15 inch lengths of barrel tubing were used, one was aluminium with an I/D of 5mm, while the other was a straighted piece of coiled copper tubing with an I/D of 4.5mm. The barrels were hooked up to a blowgun attached to a compressor and used to fire lead BBs - with a nominal diameter of 4.5mm - at 100 psi through a chronograph. Over a 5 shot string, the 5mm I/D barrel averaged 242 feet per second, whilst the 4.5mm I/D barrel averaged 279 feet per second. With an average projectile weight of 8 grains, this gives a muzzle energy of 1.04 and 1.38 ft/lbs respectively - a significant power increase of 33% over the wider barrel.
Posted: Wed Jun 22, 2011 11:29 am
by warhead052
Is it pretty much saying that the tighter the barrel, the better? Because I know that much, its just I only have 3/8" at the moment, and nothing smaller except for the 2inch long nipple.
Posted: Wed Jun 22, 2011 11:35 am
by jackssmirkingrevenge
warhead052 wrote:Is it pretty much saying that the tighter the barrel, the better?
Yes, but a bit more than that - in that a tiny difference in barrel diameter (just 0.5mm or 0.01968 inches in the example above) can make a disproportionate and extremely signifcant difference in performance, so it's worth the effort to find the closest possible fit between projectile and barrel.
Posted: Wed Jun 22, 2011 11:46 am
by warhead052
Well, for the pressure I would like to run this at, my friends will probably kill me. I tested it on my brother yesterday at 125 psi, and while the bb's spread like a shotgun, he still got hit about 50 times, and it left about 30 bruises on his legs. It was pretty funny because his face contorted in rage and he started chasing me around the house. And I also learned that I can get an air compressor from harbor freight for only $10, even though its car battery powered. I am aiming for a 1/4" or 1/8" barrel, and I am going to see about getting the body of either a SCAR or a mini uzi from a friend for it. Its going to look extremely nice, and I will hopefully find a way to put a magazine on it and what not.
Posted: Wed Jun 22, 2011 11:53 am
by irisher
I would advise against buying one of those $10 12 volt compressors. They wont have the flow you need and will die after only a few uses.
Posted: Wed Jun 22, 2011 12:02 pm
by warhead052
Yeah I know that much irisher, but I don't need high flow, and for what I would be filling it would not take very long.
Posted: Wed Jun 22, 2011 9:21 pm
by Crna Legija
warhead052 wrote:Yeah I know that much irisher, but I don't need high flow, and for what I would be filling it would not take very long.
it will brake in the first week for sure.