SpudFiles

hello, since I have finished revamping the spudinator, my bbmg, and my spray and pray gun is almost done being converted to propane (too cold to paint it will post pics after) I am thinking about a new project. I want to build a piston valve co2 powered muzzle loader. I will use 1/2 copper pipe for the barrel witch will be rifled. my question is what size should I make the valve. I was thinking 2 inch but that seems a bit over kill for a 1/2 in projectile. also will copper handle 400 psi in the cold with out bursting. I want the gun to have an effective range of about 50 yards. I would prefer 80 to 100 yards but I am unsure how do able that is. I will be using the pre made muzzle loader conical projectiles with a powerband sabot to seal the air something like this,


what do you guys think? is it possible?
thanks in advance.

From my experience I doubt that 400 psi will be enough with a round that heavy. It just wouldnt come close to what black powder can do.

And to answer a few of your questions, yes, 2 inch is over kill for the barrell. 1 inch seems more reasonable. And no, there will not be any problems using copper in the cold. Copper is pretty dang resilliant to the cold.

jook13 wrote:From my experience I doubt that 400 psi will be enough with a round that heavy. It just wouldnt come close to what black powder can do.

I'm sure performance would be perfectly adequate, there are plenty of big bore air rifles out there that are used for shooting large...er, "targets" successfully of similar calibre. Granted, they tend to use pressures a little higher than 400 psi, but then again they don't have valves as efficient as what spudders tend to use.

Heavier rounds in pneumatics mean more muzzle energy, this of course is at the expense of reduced velocity and therefore makes it harder to hit your target, but if you do, the effect will be devastating.

Should be possible, a 1" valve should be plenty, the main thing is making a fast opening one. copper will hold as long as your solder joints are up to scratch

... but with a heavy round, you will get significantly higher velocity even with the step up from a 1/2" to a 3/4" barrel (using a sabot) around 100ft/s with the same valve and chamber!

You might want to check this:
http://www.spudfiles.com/forums/lupara- ... 16624.html

Brian that is a cool sawn off.

do you think a 12 gram would work for this project?

What is the safe maximum pressure I can take copper up to with Co2?
thanks for all the input so far.

I've taken copper to 79 bar, and almost lost my front teeth as a result.


Long story.

Don't use copper, use malleable thickwalled steel and be safe.

Anyway, I suggest you start out a little safer and use 100 psi like everybody.

100 psi and a longer barrel gives you plenty of power.You need to understand the basics before attempting to use 900 psi CO2.
Not many unregulated guns have been made.

The gun needs to have a pretty good velocity and needs to crack through a 2x4 at 50 yards, is this possible with regulated Co2? what metal is safer/ cheaper at what psi? (I am sorry for all the questions but this is still a rough idea)

Also would a QEV or piston valve be better for what I am trying to do.

edit I have some experience with regulated co2, this is not my first co2 gun.

Steel pipe and fittings, I recommend no larger than 1/2 inch.


If this doesn't cut it I don;t know what will.

here http://www.spudfiles.com/forums/viewtop ... tml#218238

jackssmirkingrevenge wrote:Heavier rounds in pneumatics mean more muzzle energy

It's a law of diminishing returns.
I've been looking into this, and below velocities below about 60% of the speed of sound in the propellant gas, it seems the results can be predicted by some equation pushing.

Now, through fitting curves to the results I have, it seems that at least in the situations I've been looking at, muzzle energy increases in rough proportion to (projectile mass^0.15). This exact power will differ slightly due to cannon design.

As a very rough rule, to increase muzzle energy by 10%, the projectile mass will up by 90% - and with it, recoil will double - and this also means velocity cuts of about 25%.
That's not a great trade off really.

Now, to get back to an important point - when I said "60% the speed of sound in the propellant gas", above this velocity is where pneumatic cannons start to become far more inefficient very quickly. In this range, cannon muzzle energy is roughly proportional to (projectile mass^0.4) - again, in the cases I'm looking at.

Personally, if looking to achieve a decent compromise in a pneumatic, I'd look for a projectile which has a velocity of approximately this 60% - so between about half the SOS and 2/3rds the SOS in the propellant gas. With CO2, this will be between about 425 and 550 fps.

I'll do a fuller write up of my observations on this some other time, but I'm bored of typing this post now.

Hmm, no one has mentioned the fact that 1/2" copper is NOT 1/2" id.

Not really a factor if you go with steel, but a point to consider none the less.

Another point to ponder, is how exactly are you planning to rifle your barrel?

Without rifling, and the resultant spin on the projectile, your slugs will tumble uselessly in the air, and any hope of accuracy, even at 50 yards, can be forgotten.

This may offer you some ideas.

http://www.spudfiles.com/forums/high-pr ... 12803.html

You should check out www.dixiegunworks.com

its a black powder supply company and you can buy a .50 caliber barrel. their not cheap, expect to spend at least $120, but if you really want it thats how you do it. plus its rifled and will be fairly accurate.

please note i do not intend for you to use black powder, only the barrel for a pneumatic rifle.

Gippeto wrote:Without rifling, and the resultant spin on the projectile, your slugs will tumble uselessly in the air, and any hope of accuracy, even at 50 yards, can be forgotten.

The man makes a good point, an effective rifled barrel is probably the most challenging part of your project. I would recommend upping the calibre to 3/4" and using shotgun slugs as ammunition, they should fit pretty snuggly. Also, remember that the base area of a projectile is where the pressure acts and is therefore directly proportional to the available power. This means that by increasing your calibre to 150%, you've increased the available power by 225%

If I had GGDT here I'd run some numbers but as a guesstimation, such ammunition in say a 5 foot barrel with at least 1:1 chamber:barrel ratio, a good piston/QE valve and around 150 psi would be more than enough for your purposes.

I think I will use 20 gauge slugs in the sabot. I belive they are exactly 3/4, and I will not have to rifle the barrel because the Remington 5/8oz hollow point rifled slugs are designed to be used in a smooth bore barrel, so the sabot has rifling on it. I have had great success with these in my shot gun, I just need to figure out were I can just buy the the slug in the sabot short of the shell powder ect.