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Discussion Starter · #1 ·
Pretty cool!

http://www.ctmuzzleloaders.com/ctml_experiments/rbballistics/rbballistics.html

I did some playing with it, and came up with some interesting numbers:
Code:
<br />
Caliber: 0.50 Inch Bullet Weighing 130.0 Grains<br />
Aim Point: 10 Yards with 0 MPH Crosswind<br />
Sight Plane: 1.0 Inches<br />
Muzzle Velocity: 175 fps<br />
<br />
  0 Yds: FPS/fpe =  175/  8.9 Drop =   -1.0 in. Drift =  0.0 in. TOF = 0.000<br />
  5 Yds: FPS/fpe =  169/  8.3 Drop =    1.1 in. Drift =  0.0 in. TOF = 0.087<br />
 10 Yds: FPS/fpe =  163/  7.7 Drop =    0.0 in. Drift =  0.0 in. TOF = 0.177<br />
 15 Yds: FPS/fpe =  157/  7.1 Drop =   -4.6 in. Drift =  0.0 in. TOF = 0.271<br />
 20 Yds: FPS/fpe =  151/  6.6 Drop =  -13.2 in. Drift =  0.0 in. TOF = 0.369<br />
 25 Yds: FPS/fpe =  145/  6.1 Drop =  -26.0 in. Drift =  0.0 in. TOF = 0.470<br />
 30 Yds: FPS/fpe =  140/  5.6 Drop =  -43.9 in. Drift =  0.0 in. TOF = 0.576<br />
 35 Yds: FPS/fpe =  134/  5.2 Drop =  -67.0 in. Drift =  0.0 in. TOF = 0.685<br />
 40 Yds: FPS/fpe =  129/  4.8 Drop =  -96.4 in. Drift =  0.0 in. TOF = 0.800<br />
 45 Yds: FPS/fpe =  124/  4.4 Drop = -132.1 in. Drift =  0.0 in. TOF = 0.918<br />
 50 Yds: FPS/fpe =  118/  4.1 Drop = -175.5 in. Drift =  0.0 in. TOF = 1.042<br />
 60 Yds: FPS/fpe =  109/  3.4 Drop = -288.7 in. Drift =  0.0 in. TOF = 1.307<br />
 70 Yds: FPS/fpe =   99/  2.9 Drop = -443.1 in. Drift =  0.0 in. TOF = 1.595<br />
 80 Yds: FPS/fpe =   91/  2.4 Drop = -650.2 in. Drift =  0.0 in. TOF = 1.911<br />
 

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I ran it again, changing the ammo to a 100 grain .50 cal marble. It appears (as expected) that a heavier projectile will maintain its speed longer, and thus have less drop.
Code:
<br />
Caliber: 0.50 Inch Bullet Weighing 100.0 Grains<br />
Aim Point: 10 Yards with 0 MPH Crosswind<br />
Sight Plane: 1.0 Inches<br />
Muzzle Velocity: 175 fps<br />
<br />
  0 Yds: FPS/fpe =  175/  6.8 Drop =   -1.0 in. Drift =  0.0 in. TOF = 0.000<br />
  5 Yds: FPS/fpe =  167/  6.2 Drop =    1.1 in. Drift =  0.0 in. TOF = 0.087<br />
 10 Yds: FPS/fpe =  159/  5.6 Drop =   -0.0 in. Drift =  0.0 in. TOF = 0.179<br />
 15 Yds: FPS/fpe =  151/  5.1 Drop =   -4.9 in. Drift =  0.0 in. TOF = 0.276<br />
 20 Yds: FPS/fpe =  144/  4.6 Drop =  -14.2 in. Drift =  0.0 in. TOF = 0.378<br />
 25 Yds: FPS/fpe =  137/  4.2 Drop =  -28.3 in. Drift =  0.0 in. TOF = 0.484<br />
 30 Yds: FPS/fpe =  130/  3.8 Drop =  -48.3 in. Drift =  0.0 in. TOF = 0.597<br />
 35 Yds: FPS/fpe =  123/  3.4 Drop =  -74.9 in. Drift =  0.0 in. TOF = 0.716<br />
 40 Yds: FPS/fpe =  116/  3.0 Drop = -108.9 in. Drift =  0.0 in. TOF = 0.841<br />
 45 Yds: FPS/fpe =  110/  2.7 Drop = -151.5 in. Drift =  0.0 in. TOF = 0.973<br />
 50 Yds: FPS/fpe =  104/  2.4 Drop = -204.8 in. Drift =  0.0 in. TOF = 1.114<br />
 60 Yds: FPS/fpe =   92/  1.9 Drop = -347.4 in. Drift =  0.0 in. TOF = 1.420<br />
 70 Yds: FPS/fpe =   82/  1.5 Drop = -552.5 in. Drift =  0.0 in. TOF = 1.765<br />
 

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Wow, pretty sharp Aaron! Did you notice in both instances that between 15 and 20 and then again at between 20 and 25 yards there is a more then 100% increase in the drop rate. That ,I think is the greatest percentage amount in the chart. Very interesting. Flatband
 

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Discussion Starter · #4 ·
Wow, pretty sharp Aaron! Did you notice in both instances that between 15 and 20 and then again at between 20 and 25 yards there is a more then 100% increase in the drop rate. That ,I think is the greatest percentage amount in the chart. Very interesting. Flatband
Yeah, that is odd. Especially since the speed seems to drop off a a pretty steady rate.

I just ran it with the same specs, except for a 248 grain Tungsten Carbide ball. It carries WAY more energy, and seems to fly quite a bit faster for a longer distance. Infact, it does not drop below 160FPS until 25 yards out!! The marble drops below that before it even gets to 10 yards.
Code:
<br />
Caliber: 0.50 Inch Bullet Weighing 248.0 Grains<br />
Aim Point: 10 Yards with 0 MPH Crosswind<br />
Sight Plane: 1.0 Inches<br />
Muzzle Velocity: 175 fps<br />
<br />
  0 Yds: FPS/fpe =  175/ 17.0 Drop =   -1.0 in. Drift =  0.0 in. TOF = 0.000<br />
  5 Yds: FPS/fpe =  172/ 16.3 Drop =    1.0 in. Drift =  0.0 in. TOF = 0.086<br />
 10 Yds: FPS/fpe =  168/ 15.7 Drop =    0.0 in. Drift =  0.0 in. TOF = 0.174<br />
 15 Yds: FPS/fpe =  165/ 15.1 Drop =   -4.2 in. Drift =  0.0 in. TOF = 0.264<br />
 20 Yds: FPS/fpe =  162/ 14.5 Drop =  -11.8 in. Drift =  0.0 in. TOF = 0.356<br />
 25 Yds: FPS/fpe =  159/ 14.0 Drop =  -22.8 in. Drift =  0.0 in. TOF = 0.449<br />
 30 Yds: FPS/fpe =  156/ 13.4 Drop =  -37.8 in. Drift =  0.0 in. TOF = 0.545<br />
 35 Yds: FPS/fpe =  153/ 12.9 Drop =  -56.7 in. Drift =  0.0 in. TOF = 0.642<br />
 40 Yds: FPS/fpe =  150/ 12.4 Drop =  -79.7 in. Drift =  0.0 in. TOF = 0.741<br />
 45 Yds: FPS/fpe =  147/ 11.9 Drop = -107.1 in. Drift =  0.0 in. TOF = 0.842<br />
 50 Yds: FPS/fpe =  144/ 11.4 Drop = -139.6 in. Drift =  0.0 in. TOF = 0.946<br />
 60 Yds: FPS/fpe =  138/ 10.5 Drop = -219.4 in. Drift =  0.0 in. TOF = 1.159<br />
 70 Yds: FPS/fpe =  132/  9.7 Drop = -321.5 in. Drift =  0.0 in. TOF = 1.381<br />
 80 Yds: FPS/fpe =  127/  8.9 Drop = -448.9 in. Drift =  0.0 in. TOF = 1.613<br />
 90 Yds: FPS/fpe =  121/  8.1 Drop = -604.2 in. Drift =  0.0 in. TOF = 1.855<br />
<br />
 

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one thing you have to mention is the kind of bands it takes to push such ammo.. for instance it would take a lot heavier band to push a 250 grain ball to 175 fps than it would to push a 100 grainer to 175. Im not even sure if i could shoot a band that would push a 250 grain ball to 175 fps, those would be stout bands!

really neat program you found though, i have a similar program but it only gives one calculation at a time..this list is very interesting.

its neat to see the energy calculation. I have been told that it can take as little as 4 foot pounds of energy to kill small game (for the record i'm not sure how true that is) so that means the hundred grainer is only good to 25 yards the 130 grainer is good out to 50 (which is farther than i thought and coincidentally what i shoot
) and the 250 grainer can kill well past a hundred yards!! wow! (assuming one could compensate for more than 600 inches of drop!) now I generally dont shoot past 25 yards or so at game, but its amazing to know that should I get good enough I could still kill at those distances.
 

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Discussion Starter · #6 ·
one thing you have to mention is the kind of bands it takes to push such ammo.. for instance it would take a lot heavier band to push a 250 grain ball to 175 fps than it would to push a 100 grainer to 175. Im not even sure if i could shoot a band that would push a 250 grain ball to 175 fps, those would be stout bands!
It would definitely take a strong band, but not twice as strong. Remember that the the weight of the shot does not effect the speed as much as how quickly the bands can retract. Tex-shooter tells me that he has made a slingshot that achieved almost 400FPS with standard ammo.
 

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The nice thing about this ballistics calculator is that it is based on lead balls (it will fill in grains when you put in dia.). Everyone should do themselves a favor and shoot lead. Hornady has full array of calibers and they are readily available and cheap. Lead is much safer to shoot because it doesn't ricochet like a steel and a 127.5 grain lead ball is only .440 in diameter and .490 is 176.5 grains.

I see that you based your calculations on 175fps which is way to slow. 175fps is better suited for shooting paint balls. If you can get your velocity up to 225-250fps, your ammo will have a more realistic trajectory.

Someone mentioned 400fps with regular ammo and I doubt that is correct. 300fps is a more realistic.
 

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I used 175 because that is the average speed of a commercial slingshot.

I am not a big fan of lead, but you are right that it is much less likely to ricochet. I don't like it due to its toxicity. I prefer steel for everyday use, and Tungsten Carbide for its superior properties. If I could find a place that sold solid copper balls I would use that over either. It safer than lead, but softer and heavier than steel, and cheaper than tungsten.

Bill said that he has gotten 392FPS before. He did say that the bands did not last long at that speed. I think he used 1/2" ammo for it. I'll bet Joerg has gotten similar speeds.
 

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You can trust what Tex and Joerg tell you. They know their is a trade off between speed and long lasting bands.
 

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Wow 392fps, that's amazing. I would like to see the rig that did that. I haven't seen Joerg post numbers anywhere near that high. I was under the impression that rubber didn't have the ability to contract much more than 300fps. I might be wrong but I think I got that number from a post from Joerg. I wonder if some kind of mechanical advantage was used.

The reason I commented on the 175fps was that I didn't think any of the members of this forum would be shooting store bought slings. So if you were going through the trouble of posting ballistic charts using the higher speeds might give better data for the members. I'm sure everyone is using the calculator now anyways, so thank you for posting it for the people that didn't know about it.

Good luck on your quest for the ultimate ammo. I don't care for the toxicity of lead, but it's the only realistic ammo at a reasonable price point. 10 USD for 100 lead is a good deal.

Happy Holidays
 

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Flatband did make 400FPS. I am going to say this again , Don't do this as the bands will slice you open if stretched enough to achieve that speed when they break!!Tex They will only last a few shots at that speed (like a max of 10)
 

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lead can be free. I have never paid a dime for my lead ammo because i make my own. my only investment was the mould, the dipper, and the charcoal. everything else I made from junk. and I get my lead from tire shops, they just throw away their old wheel weights, so most shops are happy to give you a bucket full.

everybody seems real worried about the toxicity of lead, (I have heard that several times on this forum) but its not acid, it can only hurt you if absorbed into the body. so dont carry you ammo in your mouth and wash your hands before you eat and you should be fine
my dad remembers when he was a kid Christmas tinsel was made out of lead (as well as everything else) they used to wad it up and play catch with it and chew on it and all sorts of things. I dont think your average slingshotists could handle enough lead in their lifetimes to harm themselves or the environment. we deal with such small amounts. after all at 30 or so pounds a piece, there is more lead in a couple car batteries than we would probably shoot in a lifetime.

I have seen most if not all of jeorg's videos and he does some amazing stuff, but he is not doing 400 fps with 130 or more grains of lead. If flatband can get 400 fps out of anything but a little piece of steel I wanna see this beast (and i wanna see the truck he pulls the bands with
). I can get close with a BB but not a decent size chunk of lead. for me (granted i have a pretty short draw length) 175 fps with 130 grain lead 38 round is pretty close to average, with single bands of .050 latex tapered. i cant even come remotely close to that with store bought tan surgical tubing bands, its like 120 max with those things. heck my 55 pound recurve bow only does about 190 fps! with a 500 grain arrow, and fiberglass/wood limbs store energy drastically better than any rubber type bands.
 

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Let's start off with: I am a total novice.
Right, now that that is clear, lets start my post:lol:.

About a month back, I built a slingshot out of a rough V shape from one of the trees in our garden. I used 4 (2 on each side) cheap, normal rubber bands from the local "everything" shop. Shooting small stones (I calculated an average weight at 1.6grams, or 24 grains) straight up, and timing the amount of time it took to go up and to come down again, I got an average air time going straight up of around 8 seconds.

Now, by knowing the speed at which things fall, and that it took 8 seconds to go up and down, we know it spent 4 seconds each way. With all of these numbers floating everywhere, in some kind of godly act my dad calculated the end of stroke (or, muzzle velocity if you like) speed to be at 350-or-soFPS.

So, either the recipe I used to make my slingshot was somehow super lucky and amazing, orrr, the calculations my dad and I made that day are off by about 200FPS.

IS 350FPS possible with just regular bands (I might say, they weren't cut and folded, so it was like having 4 rubber strips on either side of the slingshot fork)?

Is it even plausible?

(I have no idea how this post contributes to this thread, but it's talking about speeds, so I guess it counts, lol).
 

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I got the 392FPS with a 1/2 inch marble and single .030 bands stretched way beyond what they should have been. The slingshot that I used was my long extended fork I call Nova Star. Here is a link to my You-tube Channel you can see the Nova Star there. Tex
http://www.youtube.com/user/slingshotbill
 

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Im not sure what calculation you were using but i thing its more likely you were calculating for velocity /vs gravity and then 1/2 terminal velocity coming down.. so I dont think your calculation is right.. it couldnt have taken 4 seconds each way because terminal velocity is 39 fps squared or something like that, so it should have taken half a second to reach maximum height and 7 or so to come back down. remember it stopes up there so its just like someone dropping it at maximum height. ....that being said it is very possible to get speeds into the 300 + fps with small and light projectiles. I just got my chronograph in the mail so i will test some very light projectiles soon just to see what velocities I can get.
 
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