Does this make sense?

[ABshooter]

Say I've got an airgun that will shoot a 14.3 gr pellet at 600 fps, (which I don't) and I put a .50 cal barrel on it and load in 10 BBs, which wieghs 51 gr. How fast will it shoot the BBs? Here's what I thought:

51 (10 BBs) divided by 14.3 (one pellet) =3.56 So theres 3 and a half pellets in ten BBs. 600 (pellets velocity) divided by 3.56 (amount of pellets in ten BBs) = 168 (ten BBs velocity). Does that sound correct?

[papaburger]

i think you have to use muzzle energy (unit is feet pound) to find the speed.

sqrt(14.3 gr / 51 gr * 600 fps * 600 fps) = 317.7 fps

If there is blow-by around BB, I suspect it will be less than 317 fps.

[ABshooter]

So a gun that shoots a 14.3 gr pellet at 600 fps will shoot ten BBs, wieghing 51 gr, 300 fps?

[cozmos]

actually you will get more energy out of the same gun by mounting a barrel in larger caliber.
cos the surfacearea of the bullet is bigger and its get more efficient.
fore exampel if you take a stock crosman 2240 @ 8 joule, and put on a 10" 9mm barrel you will get 16 joule of energy.
the obowe example has been tested, and cronoed.

[Aaron]

where would you get a 9mm barrel a though?

[MCJROTC]

Also the bbs wouldnt really go anywhere becuase the air would go past them being that yhey are .177

[ABshooter]

Well I'm going to put wadding behind them, I'm not completely stupid

[Allan]

its a neat idea.. but i really dont think you would be very happy with it, i would just get a .22 rifle thats around 500 fps and snipe em tree rats... or just buy the new gamo shotgun, it comes out in june or july.

but really, i wouldnt make a shottie, ide make a .25 cal out of a 2289, that is what im going to do when i get more money. you will just have t order pellets online. or you can use #3 lead shot. from a shot gun shell

[Allan]

its a neat idea.. but i really dont think you would be very happy with it, i would just get a .22 rifle thats around 500 fps and snipe em tree rats... or just buy the new gamo shotgun, it comes out in june or july.

but really, i wouldnt make a shottie, ide make a .25 cal out of a 2289, that is what im going to do when i get more money. you will just have t order pellets online. or you can use #3 lead shot. from a shot gun shell

[ABshooter]

its a neat idea.. but i really dont think you would be very happy with it, i would just get a .22 rifle thats around 500 fps and snipe em tree rats

I've allready got one. I'm very happy with it and I'm sure it would work very well for sniping tree rats, but I would need to be a very good shot indeed to shoot flying birds, which is what I want to use this airshotgun for...

[jezX]

. i can tell you that in a 9mm gun with a 20''+ barrel the bbs go just about as fast as the 14gr pellet in .22barrel. as long as a patch is used .
hard to tell the exact speed but all bb's sink into a bord well.

[ABshooter]

I dunno where to get a 9mm barrel though...

[thudthumper]

i think you have to use muzzle energy (unit is feet pound) to find the speed.

sqrt(14.3 gr / 51 gr * 600 fps * 600 fps) = 317.7 fps

If there is blow-by around BB, I suspect it will be less than 317 fps.

i think that would be true if the same barrel were used for both the .22 and shotgun. i got the same answer using a different method:
V^2=Vo^2 + 2(a)(x)
V=600, Vo=0, i'll assume x (barrel length) is 14 inches (or 14/12 feet), and a is acceleration of the pellet.
600^2=2(a)(14/12)
a=154285.7143

F=m*a
F=14.3*154285.7143
F=2206285.714

if you use the same barrel for the shotgun:
F=m*a
2206285.714=51*a
a=43260.50421

V^2=Vo^2 + 2(a)(x)
V^2=0 + 2(43260.50421)(14/12)
V=sqrt(100941.1765)
V=317.71

NOTE: i assumed the same barrel was used for both. since you're wanting to swap barrels from a .22 to a .50 cal, you will most likely see an enormous drop-off in velocity due to the larger volume of the barrel. i.e., the air can expand throughout the .50 barrel more than the .22, lowering its pressure, and consequently lowering the force it applies to the bb's while accelerating them (relative to the .22 barrel).

also, if the length of the barrels differs, the rifle and shotgun will be accelerating their projectiles for different periods of time, also affecting velocity. honestly, there really isn't enough info here to try and predict what will happen. if you knew the total volume of all air chambers from the valve to the end of the barrel, i might could calculate some numbers for each barrel using calculus and a bit of thermodynamics...but i'm a bit rusty. heh, if you're serious about the project just try it...

[Allan]

ok, i just tried this, i rolled up a tiny square of paper, using this metal rod that just fit into the 2289 barrel. so i rolled it, super glued it, and put 5 bb's down it, its like a snake of BB's.

results, it was able to punch through 1/8 particle board stuff at 15 yards, with a 3 inch patter. i would only use this on game that is not moving, and i wouldnt use it over 20 yards.

[Jester]

Well I'm going to put wadding behind them

So it's not just hypothetical, you are planning on doing it? Nothing wrong with that, but...

Say I've got an airgun that will shoot a 14.3 gr pellet at 600 fps, (which I don't)

...does that also mean that you do have this 600fps gun which you said you don't have? There's nothing wrong with that either, I'm just wondering why you wouldn't ask about the actual gun?

I'm not criticizing you, but what is the actual gun you're going to use? An "airshotgun" would be cool if it worked well enough to be practical. I think the problem with Allan's set up is the wadding. Maybe try model rocket wadding, that would probably work better than paper. I'll be interested to find out the results of your experiment.