SpudFiles

ok, so with the ProChrono I got 400 fps on the nose at 350psi. The shorter barrel gave me around 360-370. Bumping up to 400psi only gave me around 412fps. So this means... I need a longer barrel with the higher pressures to acheive greater velocity or perhaps more ballast? I tried a longer ballast with little improvement.... ugh... more post later, gotta run.

24 gram projectile 400 feet per second 131.6 foot pounds of force.

Both would boost projectile energy but a longer barrel would give you a better return on the gas you're using anyway.


Incidentally, random question but is the aluminium tubing you use a standard size?

The ballast is US 1.5" and the barrels are 40mm I imported through Canada from Sweden. (hence the stakeout I busted up a couple years ago in my front yard). I got some 1.5" SCH 40 aluminum tube today that is actually 40mm as well, but with a larger OD. The 40mm ID I have has an OD of 1.772. The OD of the SCH40 is 1.87

I am bummed. My camera or computer is having problems connecting with the firewire cable.... I will have to try again another time. Sorry all.

Solar wrote:the barrels are 40mm I imported through Canada from Sweden.

That sounds convoluted to say the least.

Shame to hear you're having camera/computer troubles. Hope you manage to get them sorted.

Is the desire for more velocity a personal goal, or one which it'll actually be used at? Because I would not want to be hit by a 40mm paintball at 400fps!

This gun is amazing. Expert all the way around. I'd love to see that bad boy hit around 600fps or more. Stretch that barrel out!

I made a type in the earlier post... that was 400fps at 300, not 350 psi.

BIOpyro/All: The military is interested in a lethal/less lethal combination. They have given someone financing for phase I development to another company that is many years behind me in design and implementation, beside barking up the wrong tree. They are making a .50 caliber combustion that needs to have ammo switched out to go between lethal/less lethal. Completely useless. You can do that with regular shotguns. .68 caliber FN303 paintball rounds at 400fps have already killed a girl. Why the #$#% are they going to a smaller round? The 40mm rounds will not enter an eye cavity nor will they penetrate between ribs. The variable velocity with mine is achieved through a choke system or soon, a regulator that bleeds off excess pressure when turned back down. I need to hit a torso sized object at 150ft for the less lethal applications. I would go into some of the other aspects of lethality using other rounds, but I think that is against forum rules here.


I will get the camera prob fixed today I hope.

Solar wrote:The variable velocity with mine is achieved through a choke system or soon, a regulator that bleeds off excess pressure when turned back down.

Now, please stick with me, because I'm just a 14 year old... But is the choke system you are using on your gun, close to or similar to the system on the Beretta LTLX7000 Shotgun? I remember watching an episode of 'Future Weapons', and when they showed it off, it had a system where it could determine the distance of a target and release some gases to slow the projectile down to a 'Less than Lethal' velocity.

No, it uses a valve choke that restricts air flow behind the round, not by venting the barrel.

Solar wrote:No, it uses a valve choke that restricts air flow behind the round, not by venting the barrel.

Okay, I get what it does, but how?
When I think about it, there are many different ways that it could be accomplished.
Are you decreasing the pressure used to propel the round, or what?

Fair enough. Have you seen the future weapons episode with the less than lethal weapons. There is one which has an onboard computer which has to estimate the range then adjust the power accordingly. I forget the details but it might be of interest to you.

Can you PM me with the other aspects? I'm very interested in these applications, as human v human combat is gradually phased out, applications for new military technology will mostly be for controlling it's own citizens.

Biopyro wrote:Fair enough. Have you seen the future weapons episode with the less than lethal weapons. There is one which has an onboard computer which has to estimate the range then adjust the power accordingly. I forget the details but it might be of interest to you.

I'm pretty sure you are talking about the same episode as I am.

That shotgun uses a fixed powder charge so it can't limit the power it starts with.

It uses some kind of blow-by mechanism to reduce the force transferred to the slug.

Since the eclipse is pneumatic it can change the force before anything gets fired.

Very impressive gun. Well built and clean!

I got into making these things about 2 years ago. Just now I'm finally made a nice combustion one and been looking this site at other people's works.
Mine isn't nearly as nice looking as this thought. All I can say is I'm jealous.