SpudFiles

jitup wrote:
Back to the original post
how about my idea. Is it possible to get an effective 50 yards range to go through a 2x4?
and should I use copper or steel. I am thinking it will be a coaxil with a piston valve. Will it hold up in freezing temps?

If not, then I wasted a hell of a lot of my time.

Ragnarok wrote:A 180 lb hog with 29 ft-lbs? Demonstrating that is just irresponsible - 99.9% of shooters are never going to be in a situation where that's feasible and possible for them to pull off, most likely they'll wound the poor thing.

Fair points, but there is a difference between US and European hunting mentalities. In Britain for example, hunting with bows is completely outlawed as being inhumane, while in the states it's acceptable to hunt with bows and stalk the animal in question for hours or even days until it bleeds to death.

If you can guarantee a brain shot (not only a head shot, jaws, noses etc. don't count) which shouldn't be that hard at close (sub 30 yards) range, a 0.177 pellet screaming at that velocity has more than enough ooomph to punch through a hog's skull and sufficiently damage the brain to assure near instant death.

how about my idea. Is it possible to get an effective 50 yards range to go through a 2x4?
and should I use copper or steel. I am thinking it will be a coaxil with a piston valve. Will it hold up in freezing temps?

I already mentioned most of these, but to summarise, I would recommend a 0.75" co-axial pneumatic with these minimum specifications:

-60 inches of barrel
-1:1 chamber:barrel volume ratio
-QEV piloting
-120 psi of chamber pressure
-12 gauge shotgun slug ammunition or similar
-red dot sight

jackssmirkingrevenge wrote:Fair points, but there is a difference between US and European hunting mentalities.

It's somewhat bizarre.

I'm of course used to using about 11 to 11.5 ft-lbs on small targets like squirrels and rats.
I know that's enough for a clean kill with a good shot, which really calls for about 1/2" accuracy at the given range, not a challenge for a decent air rifle.

However, in the States, many people would use 10 times that energy in a .22 LR for the same job. I see that as a bit of an overkill if the target is within airgun range - out to about 50 yards. I have to go for the headshot rather than just the body shot, but I'm doing the same job with less.

But then I see things like that hog and just see extreme underkill - with a perfect shot, yes, clearly they managed it. Most people don't know when the perfect shot is, or are even necessarily up to taking it - making it irresponsible, making people think the rifle is up to things it almost certainly isn't capable of.

Having seen this, and the Airow gun video from a couple of weeks ago, I'm far from impressed with the attitude some people seem to have that it's okay to just wing it, and not kill it cleanly.

You have to remember at the same time that I'm an atheist (no religious discussion please) and a vegetarian - I don't believe that these animals are soulless, I don't think it's acceptable to leave them in pain (EDIT: Actually, I do believe them soulless, but think myself the same) - and I only take the shots I have to, because I don't agree with the killing of animals. So far it's just rats and squirrels, because you're legally supposed to deal with them, and I believe the air rifle is more humane than poisons that basically cause prolonged internal bleeding (not to mention they don't die somewhere you can't find them), and far more discriminate.

Sorry, I'm ranting again.

I don't mind the ranting because I believe EVERYONE is entitled to their own opinions with out judgment from others. But a true hunter knows the capabilites of his weapon of choice and knows the pray he is seeking. For example ( I have not and will not attempt this) it IS possible to down a deer with a sling shot and lead/ glass hunting rounds. To do this you have to know the exact shot placement, be a good marksman, and be very close to the deer. I am a hunter because my family needs the meat. I also believe in clean kills and would not use a pellet gun for any thing but a varmint. (ground hogs, chipmunks, and other things that ruin the foundations of the farm buildings)

Now back to my project, all ranting aside.
I was thinking of using a QEV as the pilot and I plan on using more like 400 psi. Is that safe to do with copper? Also since I will use 3/4 shotgun slugs, the barrel will be 3/4 copper (if you guys deem copper safe) is 1 inch copper pipe good for the chamber, or should I use a larger size pipe? If I do use copper and I choose to rifle it, dose the hardened nail techniqe show promising results?
http://www.spudfiles.com/forums/diy-rif ... t2546.html

400 psi should be perfectly safe, and you should be fine with a 1 inch chamber too as long as it's the whole length of the barrel. a word of warning though, it will likely be quite loud, so I hope noise is not an issue.

I wouldn't bother with attempting to rifle the barrel personally. Slugs which work in a smoothbore 12 gauge should be perfectly fine for a spudgun. You might not get one-hole accuracy, but if you fill to constant pressure and have a well calibrated sight, I would expect to consistently be able to place all shots at least on a target the size of a dinner plate at 50 yards.

Range estimation will be critical, as well as knowning how much hold-over/under you need at 5 yard increments away from your zeroed range.

being able to determine the distance is no problem for me. I have one of those yardage estimators that has like a view finder from a camera, than when you click it, it tells you an approximate distance in yards.

Noise is not a factor. I doubt it will be louder than a 12 ga (it would be pretty cool if it broke the sound barrier! I know this gun will not be able to)

Jack it sounds like it will be about as acurate as a black powder muzzle loader. Is this a correct assumption? (I am not to familiar with muzzle loaders)

Can any one tell me where I can buy lead slugs that are for a smooth bore? I do not want to mess with pouring slugs at this point.

Let me just confirm what was already posted. A one inch piston valve will work well enough for this, a 2 inch is unnessicary.

one last question before I go buy the materials today, what size QEV should I use as a piolt? is 3/4 adaquate or over kill?

jitup wrote:Noise is not a factor. I doubt it will be louder than a 12 ga (it would be pretty cool if it broke the sound barrier! I know this gun will not be able to)

You'll be amazed at how loud high performance pneumatics are, especially if built "inefficiently" - ie large chamber volume compared to barrel volume.

Jack it sounds like it will be about as acurate as a black powder muzzle loader. Is this a correct assumption? (I am not to familiar with muzzle loaders)

You're about as familiar as I am then

Can any one tell me where I can buy lead slugs that are for a smooth bore? I do not want to mess with pouring slugs at this point.

Surely there's a shooting outlet near you that stocks slugs for reloaders, or if not 0.75" round shot for antique black powder enthusiasts.

Let me just confirm what was already posted. A one inch piston valve will work well enough for this, a 2 inch is unnessicary.

1 inch is more than adequate, given a good pilot.

one last question before I go buy the materials today, what size QEV should I use as a pilot? is 3/4 adaquate or over kill?

That's about just right. I can pilot a 1.5" piston with a shrader, but nothing wrong with a bit of overkill in the piloting department

thank you all for all the help. especially JSR for clarifying some of the points others have made and his own as well. I may seem like I asked a lot of stupid questions but this is my first high power air cannon and I wanted to make sure what I was doing was safe fter reading
http://www.spudfiles.com/forums/viewtop ... tml#218671

one other point that just dawned on me, I have an old bike pump that uses a 1 inch piston, am I able to sacrifice the pump for the piston (cheap $5 one at marc's) or is this a bad Idea and I should just make one from scratch.

also, I can only find reloading supplies for shot shell, rifle and hand gun. No slugs. And since I am using a 3/4 barrel musket rounds wont work because they are .50 cal.

EDIT: am I able to use a valve stem to fill the tank (I will take the core out and braze it in) or should I use a quick release ?

EDIT: I was just wondering if I could use a 3/4 or 1 in QEV and have performance compreable to a piston valve without having to make the vavle which would require me to first build a lathe.

EDIT: I just realized that JSR suggested a 5 ft barrel. I was wondering if i can get away with something shorter like 3 1/2 or 4 ft? The gun will be mounted on a wood stock and I think 60in will be unwieldy. please correct me if I am wrong

Using the QEV as your primary valve is certainly an option you should consider, a QEV is after all a commercially manufactured piston valve and should give you similar performance.

If you're still intent on going to 400 psi, then perhaps you should consider musket balls in a half inch barrel. If your barrel is tight enough then accuracy should still be adequate. Otherwise, consider using buckshot in a 3/4 barrel with 12 gauge sabots. This will give you a larger impact area and compensate to some extent for deficiencies in pinpoint accuracy.

When it comes to pneumatics and power, there really isn't any substitute for barrel length. To keep the overall length down, you can consider the bullpup option- Instead of having the valve pilot (presumably a blowgun) at the position where one would normally find the trigger on a rifle (as jook13 did here), consider having the valve at the butt end and placing the grip and trigger further forward, connected to the pilot by either a rigid bar or caple system, or even a simple hydraulic system like I suggested in this thread:

jackssmirkingrevenge wrote:When it comes to pneumatics and power, there really isn't any substitute for barrel length.

Not really. In a rough semblance of order, good valve is 1st, high pressure 2nd, and barrel length 3rd at best.

For an excellent example of a bullpup cannon, I think Copperhead Prime is probably the best out there, mostly by virtue of it's vertical valve, fitting a metre of barrel into maybe 103cm of cannon.

I am making somthing like the gun Jook13 has created but larger bore and more airfolw. About the QEV, Mcmaster had a 3/4 for over $100, is this the price of one or is it a glitch. If it is actually the price I will go with a piston valve piolted by a blow gun. Is there a major power diference between 1/2 and 3/4 inch barrels? I would prefer the most power I could get for a 50 yard shot to break a piece of 2/4. If only I could find a place that sells reloads for slugs!!!

jackssmirkingrevenge wrote:

Wouldn't it be better to remove the blowgun handle and connect the rod straight to the 'pin' on the blowgun valve that opens the valve when pushed in?

@MrCrowley: Yes it would. But this is Jack we're talking about.
He deliberately builds his cannons with ways so that they can go wrong to let him he keep up appearances.

jitup wrote:About the QEV, Mcmaster had a 3/4 for over $100, is this the price of one or is it a glitch.

I'm sure you can find one for cheaper, I'm sure fellow stateside spudders can provide you with less expensive sources.

Is there a major power diference between 1/2 and 3/4 inch barrels?

For a big enough valve, you potentially have more than double the power for the larger calibre.

Wouldn't it be better to remove the blowgun handle and connect the rod straight to the 'pin' on the blowgun valve that opens the valve when pushed in?

Only if you incorporate a similar lever on the grip side, the trigger on a blowgun makes it much easier to open because of this leverage than if you were pushing directly on the pin.

He deliberately builds his cannons with ways so that they can go wrong to let him he keep up appearances.

Unfortunately, my last (55mm combustion) one works a little too well, fired a test shot in the garden and it shook the whole neighbourhood I might be leaving today week but I spotted a length of what looks like around 15-20cm pipe that would make a nice suppressor

Please keep in mind, 3/4" copper is also NOT 3/4". For your reading pleasure.

http://www.copper.org/publications/pub_ ... ndbook.pdf

If you want to buy slugs, check here;

http://www.ballisticproducts.com/bpi/ar ... slugs1.htm

Also, have a look at this. It may answer some questions for you.

http://www.spudfiles.com/forums/piston- ... 13478.html