305 fps!

[BoyntonStu]

Double red Thera-Band  tubes, new pouch,  280, 289, 305 fps!

5.2 g marble  22.4 Joules or 16.5 FPE (80 grains)

The draw was 27 pounds.  (12.4 K)

The feeling if breaking 300 fps was amazing!

[boar]

way to go

Boar

[Forum Admin]

That is very impressive energy to achieve with only 27 lb draw weight. Most magnum spring guns dont produce much more than 16 fpe, the ones that do require more than 27 lbs of force to cock. That is with leverage. Seems that rubber is a more energy efficient means of propulsion. Now if there is a way we can mechanically increase the speed of the projectile that has lower losses than the spring-air system. The multiple rubber system you mentioned before might work nicely to get the extra force needed with minimal draw effort.

[BoyntonStu]

That is very impressive energy to achieve with only 27 lb draw weight. Most magnum spring guns dont produce much more than 16 fpe, the ones that do require more than 27 lbs of force to cock. That is with leverage. Seems that rubber is a more energy efficient means of propulsion. Now if there is a way we can mechanically increase the speed of the projectile that has lower losses than the spring-air system. The multiple rubber system you mentioned before might work nicely to get the extra force needed with minimal draw effort.

The highest speed for a slingshot that I have heard about was 405 fps.

I know someone else who shot 394 fps.

These were extreme draw conditions, and band life shots could be counted on one hand.

If we could have the slingshot on a sled and move the sled a few inches at 100 fps as we release the slingshot we would add 100 fps to the speed of the slingshot.

Just a thought.

[mouz]

oh my god, i just had an idea. you could fire an airgun out of an airgun, you could have an electronic timer on the valve of the projectile.     305 fps with rubber is simply shocking. your sling shot shoots only about 70 fps lower than my pneumatic pistol 150 psi.  now i need to build one of these. how much was the clamp? i think it would look nice with a real stock though, how long is it?

[FighterAce]

Good idea.. maybe hide the mechanism and rubber inside the stock so it acts like a shield if the rubber brakes or something...

[mouz]

that is my first idea with any weapon. 

[BoyntonStu]

oh my god, i just had an idea. you could fire an airgun out of an airgun, you could have an electronic timer on the valve of the projectile.     305 fps with rubber is simply shocking. your sling shot shoots only about 70 fps lower than my pneumatic pistol 150 psi.  now i need to build one of these. how much was the clamp? i think it would look nice with a real stock though, how long is it?

Thanks,

What is the weight of the projectile that you are shooting at 375 fps?

I am shooting 80 grain 5/8" glass marbles.   (5.2 g)

The Aluminum clamp is 48" long and it cost $8.95 on sale at Harbor Freight.

http://www.harborfreight.com/catalogsearch/result/?category=&q=aluminum+clamp

It is pretty straightforward to make with hand tools.

A few other guys are making version of this as we speak.

One guy is making a side by side 2 shooter with a single trigger.

I am comvinced that the Boynton-Banger is the first of many clamp guns.

The inch by inch ratcheting make the 3 handed draw easy and safe.