New homemade gun and stock (before staining), just finished!

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
DaxSF
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Fri Jan 25, 2013 3:39 am

jackssmirkingrevenge wrote:
DaxSF wrote:Regarding the pressure, I am now buying a small compressor which will go 200~250 PSI
If it's one of these, save your money.

[img]http://i00.i.aliimg.com/photo/v0/442904 ... ni_air.jpg
[/img]

Get one of these instead: http://www.ebay.com/itm/Bicycle-Bike-Al ... 416746073d

Will give you a bit of exercise too ;)
I really don't have any use for more than that I think. The gun is already 400 FPS+ (estimated via coke can chrono test).
Boooooo! MOAR POWAH!!!!!

:D
Lol, I go to the gym :( I don't need to exercise! Just kidding, adding some plates to the bench won't hurt anyone ;)

Back on topic: LOL this is the exact same compressor I was going to buy! I actually wanted a compressor so there is an automatic charge, I hate manual pumping. The difference is only 10 PSI for the manual pump, and these kind of pumps cost well over $50 where I live, while the compressor costs more like $20..
Also I think the 6mm barrel will result in some major FPS incline because of the "snugger" BB fit (right now it just falls out of the barrel if I aim too low).
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jackssmirkingrevenge
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Fri Jan 25, 2013 3:46 am

DaxSF wrote:The difference is only 10 PSI for the manual pump, and these kind of pumps cost well over $50, while the compressor costs more like $20...
On paper, you'd be right. But the reality is that these compressors are about as useful as a chocolate teapot, and will overheat and die long before they reach 250 psi.

A manual pump can also be used anywhere.
Also I think the 6mm barrel will result in some major FPS incline because of the "snugger" BB fit (right now it just falls out of the barrel if I aim too low).
Barrel tightness is *very* important. I did a test a very long time ago:
2005 me" wrote:It's fairly obvious that the closer the barrel diameter is to the projectile diameter, the less air is wasted and therefore, more power. I decided to set up a simple experiment to see just how much of a difference it makes.

The basic setup was two 15 inch lengths of barrel tubing, 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 chrony.

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.
A projectile with 10% less diameter than the barrel resulted in 25% less energy, that is very significant.
hectmarr wrote:You have to make many weapons, because this field is long and short life
DaxSF
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Fri Jan 25, 2013 4:05 am

MAN I love eBay! Just ordered some 6mm brass tubes since the smallest diameter I could find in this entire country was this 8mm and that was only because I found it from a scrap lamp post (go figure..) :roll:
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wyz2285
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Fri Jan 25, 2013 6:36 pm

Incorporate a onboard shock pump would be a good option, but your chamber maybe too big to take advantage of the high pressure it offers.
CpTn_lAw wrote: :D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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iloveairguns
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Sat Jan 26, 2013 9:47 am

It seems to be a coax airgun... Plz take a pic from the front plz plz plz :razz:
Last edited by iloveairguns on Sat Jan 26, 2013 9:57 am, edited 1 time in total.
DaxSF
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Sat Jan 26, 2013 9:54 am

iloveairguns wrote:Is it a coaxial airgun? just asking...
Yes it is.
After finishing this gun completely (probably next week, when all the parts arrive from eBay), I plan on making a new bullpup, semi-auto with a QEV I bought.

EDIT: Didn't see the edited post. I will take proper pictures tomorrow probably.. If you're interested in taking a look at the gun, PM me.
Last edited by DaxSF on Sat Jan 26, 2013 10:03 am, edited 1 time in total.
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iloveairguns
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Sat Jan 26, 2013 10:01 am

Woah quick reply, well cool if your gonna make it a bullpup and a pic would be nice of the front, and what type of trigger system does it have? Is it the schrader type?
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