My 1st Rifle

joe blogs · Fri Mar 23, 2007 6:01 pm

I am not a fan of ball valves anymore but i cant find a solnoid that is small enough in width to fit on the top of the stock and not look clumsy. could anyone please tell me where to find small sprinkler valves that can hold high pressure.

joe blogs · Fri Mar 23, 2007 8:30 pm

Since as you know that my marble gun is my first pneumatic you should assume there are many mistakes. Just three days ago it would not stop leaking and because one of my mistakes was to glue everything onto the stock i could not remedy the leak so unfortunately i had to destroy the stock trying to get all the parts out. But this has been a mixed blessing because now i can fix all my mistakes and i have acquired a .22 gun barrel which i am modding at the moment to fit into my new improved pneumatic. Now it will require less volume in the pressure tank and be much more accurate because of the professionally rifled barrel. The loading will be quicker (breach loading and smaller pressure vessel) and because of a smaller pressure vessel so i can incorporate a onboard pump. The only bad thing is that i am going to use the old ball valve because i dont have enough money at the moment to buy a good electronic valve.
The mistakes i made were many, these are just a few (i am posting this so that other new people to spud files wont make the same costly mistakes)

:i made it so it was muzzle loaded, bad mistake, the loading shooting time is way to long.
:cant strip down the parts, another bad mistake because i had to destroy a stock that took forever to build because of one damn leak.
:trigger in awkward position,
:smooth bore barrel
:ergonomics are just a little wrong
:doesn't have an onboard pump

Deactivated 1 · Fri Mar 23, 2007 9:34 pm

Hi guys. I have been in contact with Joe Blogs and he has sent me a short clip of his gun in action. I'm just uploading it to youtube and it should be up in a minute (I'll link you when it's ready). He also sent me a sound clip of it being shot at a 10m target, which I'm going to double-check for firing speed

Edit: Okay, I calculated the firing speed to be about 500 fps based on the sound file he kindly send me. Here is a snap of the sound file with scale, so you can recalculate it as you wish from different points:

Also, he asked me to upload the video of his weapon in action. Here it is:

(Very short - about 2 seconds)

integral · Sat Mar 24, 2007 2:07 am

dude very nice, ur gun has been a primary inspiration to my current design.
a quick question, how much more accurate is the rifled barrel compared to ur old smooth bore?

shud_b_rite · Sat Mar 24, 2007 4:51 am

Um i calculated the speed to be 288.18 m/s or 945 fps.

You have to remember that the time it takes for the sound to travel from the target (10m away) to the microphone is 0.0303 seconds (speed of sound at 330m/s). So you subtract 0.0303 from 0.065 and you get 0.0347. So that is the true time it took to travel 10m (assuming that the microphone is held close to the gun).

Therefore 10 / 0.0347 = 288.18 m/s 945 fps (big difference to 504 fps)

Sorry to get all technical and stuff but remember that the speed of sound is quite slow so you must account for it to get an accurate measurement.

Deactivated 1 · Sat Mar 24, 2007 4:55 am

At face value I would say 945 fps is incorrect. It would simply not be possible for this gun design. Whether that's a calculation error, an error in measuring target distance, or something else - I am not sure as this is not my gun.

shud_b_rite · Sat Mar 24, 2007 5:08 am

Whoa something in my head just clicked and it just occurred to me that 945 is SH*T fast. Well thats what i calculated using the diagram above, maybe it has been speed up. Or maybe it wasn't actually 10m.

Maybe someone should re calculate it because im quite tired at the moment, i could have easily made a mistake.

CpTn_lAw · Sat Mar 24, 2007 6:28 am

hey shud_b_rite, you're right actually. a lot of the things we hear are past. When you shoot a pellet rifle to a target at 40 meters, you here almost instantly your shot, and then, 1/3 " you hear it hit the target. actually, it hits it before. and your method is correct.
The simple example, is from where you're sitting. If you're sitting next to the target, the shot and the hit will seem to be the same.

and , you're actualy right cause i did some tests with my marble rifle too...
With the above method i had 700 fps. and considering the speed of the sound returning the hit noise, i had a beautiful 900 fps.
so, don't joke with marble guns, they are as powerful as black powder pistols.

joe blogs · Sat Mar 24, 2007 5:29 pm

Integral, I am using a .22 barrel of an old gun and it is so much more accurate. The reason its more accurate, is of coarse because of the rifling but the ammo(.22 airgun bullets)has a big part to play in that accuracy(plus way more aerodynamic). If you were to rifle a 1/2 inch barrel to shoot marbles it wouldn't really make it more accurate. I think it has got more to do with the wadding technique.

Here is a person that has acctually tested wadding vs rifling
look towards the bottom of the page in a secton called "final accuracy" and "rifling the barrel"
http://www.sentex.net/~mwandel/cannon/air_gun.html

The audio file was recorded one metre to the left of the exact middle point inbetween me and the target. I have also factored in the speed of sound into my equation. the round thing being the barrel(target)

medic · Sat Mar 24, 2007 7:46 pm

Man i love this rifle, this one has inspired me to go make my own with a few mods

Looking forward to seein your second rifle

Marshygunner · Sun Mar 25, 2007 8:58 am

Very realistic. I think that is one the coolest guns i've ever seen. Where did you find the stock?

joe blogs · Mon Mar 26, 2007 1:44 am

Made it. Took alot of time sanding and planeing it.

shud_b_rite · Mon Mar 26, 2007 2:08 am

Can I ask what size ball valve you used?

joe blogs · Mon Mar 26, 2007 3:34 pm

About 3 and a 1/2 centimetres which is about 1 and a 1/4 inches.

mattf · Tue Mar 27, 2007 5:28 am

very very nice gun good job