Catapult ammo questions.

  • Hey Guest, Early bird pricing on the Summer Moot (29th July - 10th August) available until April 6th, we'd love you to come. PLEASE CLICK HERE to early bird price and get more information.

demented dale

Full Member
Dec 16, 2021
737
361
57
hell
Could anyone please explain to me the reasons why people use various sizes of ball bearings for catapults. I shoot 10 ml from a black widow but thats coz i have never tried anything else and dont even know if that is best. As ever I am certain that someone on here can definitely answer this. Thank you in advance,
 

Dave Budd

Gold Trader
Staff member
Jan 8, 2006
2,895
321
44
Dartmoor (Devon)
www.davebudd.com
Same as ammunition for any other weapon. Bigger balls have more stopping power, so if hunting will allow larger prey to be taken. But the heavier ammo needs stringer bands to allow you to send it very far or fast (flatter trajectory is generally better for aiming, so speed is essential). 12mm balls will have more stopping power, but 8mm will likely be faster. Chances are anything bigger than a 12mm lead or 14mm steel ball would be too heavy to be of any use except at very close range

I think 10mm is a good middle ground, but maybe biased towards target shooting as it allows for a fast shot without insanely strong bands, whilst also being less affected by wind than a smaller ball would be and gives you something to hold in the pouch of the catapult.

You could buy some different sizes and see what you prefer. ;-)
 

Crac

Member
Apr 5, 2023
33
21
North
If you are target shooting it makes sense to limit the draw force since your focus is maximum accuracy. The same mindset can be applied to the bands, by lowering the strain the bands are more forgiving. You aim using the fine control muscles, if draw force is varying a lot vs position it’s very hard to be accurate. ‘Slower’ bands also make the release is much easier this affects accuracy a lot. With the pouch, you maximise feel. Match the ammo to the above and it’s pretty small. But ultimately it’s all personal preference, if you are confident with the setup you can practice more.

There might be something to be said that smaller holes in the target is a good thing. After 3-5 shots, I was passing every follow up through the hole. 1/4” or 6 mm was the fashion a few years ago, down from 8 mm.


For competitions it would depend on the rules. Chronographs tended to need shot of a certain size to work. So the speed competition used 6 mm or 1/4”. The brand of the slingshot rubber mattered a lot, some rubber was just faster than others. 100% latex was very highly rated… You didn’t go faster. Thinner rubber tended to be faster (but this topic is complicated!). Hot rubber was faster too (heating wasn’t cheating!). High strain, highly tapered bands, very small and very light weight pouches help too. Plus a long draw was essential too.


For power competition there was a minimum speed to qualify (180 fps). I would have set the speed at ~171 fps, so each gram would be 1 ft-lb. Also note chronographs have their own minimum speeds some around 100 fps. With big energy figure: It’s a lot easier to accelerate a much bigger projectile from zero to slow, that to accelerate something small to fast. Large ammo also gets really difficult to accurately release or pass through the fork. So serious entries where casting their own lead slugs. The draw force and holding the fork of the slingshot true is also a major problem, It’s not just the strength in your biceps.


With hunting things are different again, but the politics was strong with this topic. How you trade speed/accuracy at range vs momentum is largely your business. You want the shot fast enough to reduce your hold over target (compensating for drop), but not so fast it your leaving momentum on the table so to speak. My take is: If you were squeamish over a chronograph you weren’t good enough.
 

stonepark

Tenderfoot
Jun 28, 2013
94
49
Carse of Gowrie
Could anyone please explain to me the reasons why people use various sizes of ball bearings for catapults. I shoot 10 ml from a black widow but thats coz i have never tried anything else and dont even know if that is best. As ever I am certain that someone on here can definitely answer this. Thank you in advance,
Perhaps you are now at the stage a visit to the slingshot forum is in order.
 

demented dale

Full Member
Dec 16, 2021
737
361
57
hell
Same as ammunition for any other weapon. Bigger balls have more stopping power, so if hunting will allow larger prey to be taken. But the heavier ammo needs stringer bands to allow you to send it very far or fast (flatter trajectory is generally better for aiming, so speed is essential). 12mm balls will have more stopping power, but 8mm will likely be faster. Chances are anything bigger than a 12mm lead or 14mm steel ball would be too heavy to be of any use except at very close range

I think 10mm is a good middle ground, but maybe biased towards target shooting as it allows for a fast shot without insanely strong bands, whilst also being less affected by wind than a smaller ball would be and gives you something to hold in the pouch of the catapult.

You could buy some different sizes and see what you prefer. ;-)
Thanks Dave . Thats helpful and what I sorta figured. I think I might try some smaller shot and see how I get on.
 

demented dale

Full Member
Dec 16, 2021
737
361
57
hell
Could anyone please explain to me the reasons why people use various sizes of ball bearings for catapults. I shoot 10 ml from a black widow but thats coz i have never tried anything else and dont even know if that is best. As ever I am certain that someone on here can definitely answer this. Thank you in advance,
Just to add I am quite new to slingshots so dont really know a great deal about them. I'm a reasonable shot on my day but thats about it.
 

BCUK Shop

We have a a number of knives, T-Shirts and other items for sale.

SHOP HERE