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Discussion Starter · #21 ·
I need 248 fps with the 44cal do-it mold lead balls to reach 15 ft/lbs. Right?
The only way you can be certain of ball weight is to weigh them. Your alloy can vary weight by quite a bit. I have two Do-It molds and my current batch of .44 balls (actual diameter .429) cast mostly from wheel weights weigh 116 grains. To make it easy, here is an an Excel spreadsheet that will do the math for you. It gave me 242 fps with my balls for 15.09 lb/ft.

attachicon.gif
AmmoCalc.xls
Do I need a special scale?
Yes, but they are cheap. I have an AWS AC-Pro 200, accurate to ,01 gram. It cost me $20.00. I bought a calibration kit with it and shipping was free.

http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=aws+scale
 

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Discussion Starter · #22 ·
I need 248 fps with the 44cal do-it mold lead balls to reach 15 ft/lbs. Right?
The only way you can be certain of ball weight is to weigh them. Your alloy can vary weight by quite a bit. I have two Do-It molds and my current batch of .44 balls (actual diameter .429) cast mostly from wheel weights weigh 116 grains. To make it easy, here is an an Excel spreadsheet that will do the math for you. It gave me 242 fps with my balls for 15.09 lb/ft.

attachicon.gif
AmmoCalc.xls
Do I need a special scale?
Postal scales work well.
Many postal scales are only accurate to .1 ounce, which is 43.74 grains or 2.83 grams. If you do use a scale of unknown accuracy, weigh 50 or more balls at once to reduce the error.
 

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I need 248 fps with the 44cal do-it mold lead balls to reach 15 ft/lbs. Right?
The only way you can be certain of ball weight is to weigh them. Your alloy can vary weight by quite a bit. I have two Do-It molds and my current batch of .44 balls (actual diameter .429) cast mostly from wheel weights weigh 116 grains. To make it easy, here is an an Excel spreadsheet that will do the math for you. It gave me 242 fps with my balls for 15.09 lb/ft.

attachicon.gif
AmmoCalc.xls
Do I need a special scale?
Postal scales work well.
Many postal scales are only accurate to .1 ounce, which is 43.74 grains or 2.83 grams. If you do use a scale of unknown accuracy, weigh 50 or more balls at once to reduce the error.
This is the scale that I use, and it is wonderful.

http://www.leevalley.com/en/garden/page.aspx?p=68352&cat=2,40725

It weighs in about any units you want. It has a tare function so you do not have to worry about the weight of the container. It is small and compact ... shuts off automatically when not in use. Great for weighing ammo.

Cheers .... Charles
 

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I used my homemade Beankung tube shooter.

Simple Shot Medium tubes with a Performance catapults pouch.

Overall length 12 1/4 inches, pseudo tapered approx. 6 3/4" loop, 5 1/2" single

1/2" steel from Simple Shot

Butterfly draw approx. 53"
 

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Hey Bean! That was some mean shooting! I had to laugh watching your eyes as you were stretching to do that full draw!!!! By the way, do your knuckles drag the ground when you walk??? :rofl: Yeah .... if we all had longer arms, we would all shoot a lot faster ...

Cheers ....... Charles
 

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Hey Bean! That was some mean shooting! I had to laugh watching your eyes as you were stretching to do that full draw!!!! By the way, do your knuckles drag the ground when you walk??? :rofl: Yeah .... if we all had longer arms, we would all shoot a lot faster ...

Cheers ....... Charles
Lol .Glad you enjoyed it Charles. My knuckles are ok but, I am feeling it in the middle of my back. :)

Nice one bean! Thump!
Thanks Ben
 

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Here we go!

I hesitated to enter this power-fest because I wanted to have a setup that I could shoot accurately and deliver the pound-footage we're looking for. I've tried shooting butterfly on several occasions and always sucked at it so I didn't want to use something where I would have to draw past my usual anchor. Having huge power without being able to use it is an exercise in "self-gratification", if you know what I mean :naughty:

So with that in mind I rigged up my homemade starship with a set of doubled Theraband silver cut 1"x 3/4" with an 8" inactive length. My anchor point draw with this rig is 48", so I'm really working these bands! Ammo is 5/8" steel weighing 15.44 grams.

There's probably another 10-15fps to be had if I drew and released quicker but shooting 5/8" at 200fps in the house gives me a little pause to make sure everything is right!

 

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Hey MJ,

According to at least one ball bearing manufacturer, 5/8 inch chrome steel bearing weighs in at 16.44 grams, which is 253.71 grains. You said 16.44, but in your write-up you gave it as 15.44.

http://americandad.biz/chromechart.htm

By my calculation that is 24.4 fpe. So the calculations on your phone app are consistent with the proper weight for that size of steel ball.

Cheers .... Charles
 

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Hey Bean! That was some mean shooting! I had to laugh watching your eyes as you were stretching to do that full draw!!!! By the way, do your knuckles drag the ground when you walk??? :rofl: Yeah .... if we all had longer arms, we would all shoot a lot faster ...

Cheers ....... Charles
Talking about longer arms. Is there a length limit on 'starships'? ;)
 

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Hey Bean! That was some mean shooting! I had to laugh watching your eyes as you were stretching to do that full draw!!!! By the way, do your knuckles drag the ground when you walk??? :rofl: Yeah .... if we all had longer arms, we would all shoot a lot faster ...

Cheers ....... Charles
Talking about longer arms. Is there a length limit on 'starships'? ;)
If you go much longer than +20" you'll probably have trouble loading it. The one I shoot is half the size of my blowgun but packs considerably more wallop!
 

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Congrats Ol' Bean! That is some serious power.
Thank you Henry. My new goal is to break 30 ft/lbs. ( Henry, l really like your profile photo.)
I have every confidence we'll be seeing 30+ lb/ft from you as soon as the weather warms. We old geezers will be happy with 20.

I like my profile picture, too and really wish I looked that studly all the time. LOL!
 

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Discussion Starter · #39 ·
Hey Bean! That was some mean shooting! I had to laugh watching your eyes as you were stretching to do that full draw!!!! By the way, do your knuckles drag the ground when you walk??? :rofl: Yeah .... if we all had longer arms, we would all shoot a lot faster ...

Cheers ....... Charles
Talking about longer arms. Is there a length limit on 'starships'? ;)
Glad you asked. Aside from bragging rights, the main purpose of the SSF 300 Club is to explore the limits of what is possible with rubber powered slingshots. The only limitations on equipment are;

1. Rubber power only.

2. 1 gram minimum projectile weight

3. the frame must be held in one hand and the pouch drawn with the other.
 

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O.K., thought I would give it another go with my CombowSling. For some time I have been saying that in the ranges appropriate for slingshots, heavier ammo generates more energy than lighter ammo, in spite of the decrease in velocity. Soooo, I went for heavier ammo. Those slugs in the video weighed on my scale at 232 grains for the lightest one. Here is the video:


The velocities were 191.3, 186.6, 188.4, and 184.0, all in fps, and all within 5% of each other. By my calculations, that gives 18.85 fpe. Just trying to claw my way off of the bottom. I think I just crawled past Henry, but to really move up, I am going to have to fabricate some other band arrangement.

Cheers .... Charles
 
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