SpudFiles

G'day lads,

Does anyone have a clue what the penetrative power of a 3.2g 6mm lead ball with 400psi and a 1m long barrel would be? I'm thinking it's gonna be something pretty decent, well....I'm hoping it will be something pretty decent .

Cheers

<A HREF="http://www.thehalls-in-bfe.com/GGDT/index.html">GGDT</a>

Nah I know that but I'm not too sure with what it would mean damage wise. It says 45 foot pounds, frig knows what that means haha.

Well then make some balistics jell and shoot it I guess. Have you shot anything with it before?
What's the velocity?

The gun is just about complete. The 360psi shock pump is arriving tomorrow and I'm collecting the barrel aswell. GGDT said at 400psi with the 3.2g 6mm lead ball, 643fps. I sleaved a 5/16 barrel in my marble gun and shot it at 110psi. The power wasn't too bad. Just about went through 10mm MDF board and rips through jam n milo lids pretty easy so I reckon the power will be pretty damn good.

Well 45 foot pounds is 61 joules. Most airsoft guns are around 0.5 joules. If an airsoft gun can penetrate an aluminum can (just) then you could only imagine what a lead ball with 61 joules behind it will do.

A 6mm lead ball has a volume of 0.113 cm³. Lead has a density of 11.34 g/cm³, therefore it will weigh 1.28 grams, I don't know where you got the 3.2 grams from.

For the sake of comparison, a typical air rifle has a muzzle energy of 10-15 ft/lbs. A 0.22 rifmire round has around 110 ft/lbs.

With your the pressure and barrel length you specified, a big enough chamber (at least the same volume as the barrel) and a good valve will give you very decent power.

Cheers guys, thanks alot. Jack, the piston I'm going to be using will be epoxy. I was going to use hot glue but I heard you have to constantly lube it up due to the ammount of friction it can have.

Well thats changed GGDT a fair bit, 882fps with the 1.28g lead ball, with 32ft/lb.

What sort of epoxy will be using? I'm sure you've taken a look at my tutorial, epoxy pistons can be tricky but if you take enough care the benefits are worth it.

Not suggesting that you should shoot anything living here but to give an idea of power levels, have a look here - air rifles of around 30 ft/lbs can reliably take game as large as coyotes at reasonably close range (50 yards or so).

I'm just going to be getting some Araldite. It's all I can afford unfortunatly. I've seen your tut's many times, I wouldn't attempt it if I didn't

Shite....I had no idea that this gun could be as powerful as GGDT says. Just crazy...

Mitchza89 wrote:I'm just going to be getting some Araldite. It's all I can afford unfortunatly. I've seen your tut's many times, I wouldn't attempt it if I didn't

Shite....I had no idea that this gun could be as powerful as GGDT says. Just crazy...

Yeah, I tried to scale my gun into GGDT but no matter what I did realistically, I couldn't get it to shoot a golf ball 380m on GGDT like I have in real life.

I've never tried to make one out of Araldite to be honest, it dries a bit differently from the marine epoxy I use for casting. Make sure you mix it very well to ensure it hardens properly. How big will you be making it? For my 6mm pistons I usually cast in a 5mL syringe tube that I use as the piston tube, like so:

Yeah I know what ya mean Crowley, the only way I'm going to really know is if I make some Bal Gel and get a chrony.

Jack, thats a good idea. I'm going to be using a 1/2in Tee. I'm going to be lubing up a 1/2in nipple and using that as the mound for it. Should be good.

Whats the best stuff to use for stopping the epoxy sticking to the mould?

grease, KY, anything slippery. You don't need to apply it too thickly, just smear it on all the surfaces then wipe it off leaving only a thin film.

Edit: If you,re using araldite, I think a good idea to make a piston would be to have a core made of a section of wooden dowel or similar (say 5mm diameter less than the tube diameter) and use the araldite to fill in the gap.

Way ahead of ya mate. Exactly what I was thinking. Yet again...I've changed my design. This time, I've just made it as simple as possible. It's still going to be shotgun based but I'm going to use what Law and BtB have used before, the ball valve trigger with the curled grip. I hate copying but I just love the look of it plus knowing me, I'll give it my own special touches anyway. All in all, I still reckon this will be a great looking gun and have the power to match it.

One more thing, would spray cooking oil do the trick to stop the sticking? I don't see why it shouldn't work.

All the best.