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pumatic airsoft gun help ? Answered

Ok so heres my situation. About 6 months ago I made my own pneumatic airlift sniper but even though I could get about 80 lbs of pressure stored up before I pulled my trigger my sniper only shot as far as my 300 fps gun. My question is why cuz I had a lot more force in my pneumatic sniper then my other gun and it doesn't seem to matter. My sniper was made of a metal nipple about 9 inches long and 2 inches in diameter. I then put a cap on one end and a reducing coupler on the other. I drilled a hole in the cap and inserted a valve that allowed me to attach the chamber to a bike pump. On the end with the reducer I then added a ball valve that worked as my trigger. After the ball valve was another reducing coupler that brought the size down from an inch to 1/2 an inch. Into this coupler I screwed a break line about 50 cm long(sorry about the unit change I don't remeber its length in inches) and it fit the bb very nicely. I also added a little contraption I made from paper clips that allowed the gun to be tired downward without the bb falling out. However I don't believe this was the problem as I fired the gun when their was just a wire across the back of my breakline ,to keep the bb from falling into the gun ,and the distance seemed the same.
I made sure every connection before the ball valve was sealed well except that the gun did leak at a rate of 20 lbs for minute because of a bad connection with the valve that connected with the bike pump. If you need more info just say so in the comments but I don't have the gun with me right now so all i have to go off of is my memory. Thanks for your help I really appreciate it. : )

9 Replies

Downunder35mBest Answer (author)2017-02-01

Air rifles use a lot of pressure, far more than you can supply with a bike pump.
Volume is to be looked at too.
If you have a standard bore for pellets but connect to a 1/4" ball valve you loose a lot of air volume and pressure before it reaches the barrel.
Piston operated models have the connection as close and short as possible for a reason.
If you look at paintball rifles or CO2 operated air rifles it is also evident that a short burst of extreme high pressured gas is used instead of using the required barrel pressure.
This is so the pressure once the pellet goes down the barrel is at the correct levels.
High pressure models often incorporate an expansion chamber to limit condensation and allow for the use of trigger parts with a lower pressure rating.
If you need pressure in a rife than you simply don't anything reducing it between valve system and barrel.

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Josehf Murchison (author)2017-02-01

What is the ballistic coefficient of your projectile?

Airsoft projectiles tend to be light and large with little inertia to cut air. (Ballistic coefficient.)

Air rifle projectiles tend to be small and heavy with lots of inertia to cut air so they travel farther.

Next there is spin many air rifles have rifling to spin the projectile.

Most airsoft guns are smooth bore and don't spin the projectile.

A fair comparison would be a shotgun and a 22 rifle.

Shotgun full choke best at a max of 75 yards; depending on shot deadly but not accurate out to 500 yards.

22 rifle best at max 100 yards deadly but not accurate up to 1 mile.

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um I don't quite understand but its an airsoft gun not a bb rifle so light bb

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Airsoft, BB gun, 22 rifle, or shotgun, it is all ballistics.

The shape, weight, and size of the projectile is its ballistic coefficient.

Take a smooth golf ball with no dimples and hit it, it travels 50 yards.

Take a golf ball with dimples and hit it and it travels 100 yards.

They are the same speed, size and weight, but the shape is a little different.

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Yes it is; but when you clue into its weird properties you can figure out what it is doing.

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inconceivable1 (author)2017-02-01

Ok I can make he sniper again what should I improve?

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rickharris (author)2017-02-01

Friction with the ammunition and the barrel

Slow release of the pressure.

Your loosing more pressure than you think

Too narrow a passage between store and barrel limiting air flow.

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