Saturday, February 23, 2013

Slingshot Projectile Velocity Demystified..

 Slingshot Projectile speed for hunting? Misconceptions and facts from work in the field.


In many places on the internet forums for slingshots hosted by slingshot enthusiasts and also in various searches one finds this common question asked by aspiring slingshot style hunters. How fast does my slingshot projectile have to travel for hunting smallgame? Although it is a very good question it is also a very misleading question, simply because it is a vague question one that all too often generates many answers.
 Sadly this question generates the opinions and advice of armchair hunters and theorists or the hobbyist non hunting slingshot enthusiasts who have seen one too many videos of a fellow shooting his slingshot projectiles through a chronograph and then calculating "foot pounds or joules" which is a system used in fire arm ballistics  and unrealated to the use slingshot projectiles.
Nothing wrong with a hobby right? Of course not, but hobbies and real world field results on the same subject are always different. Studying the potential kinetic force made possible by a rubber powered projectile is great.
 Knowing the projectile speeds a rubber powered slingshot  is generating for the harvesting of smallgame is even better than theory.
Before I go on to debunk some of the claims of slingshot projectile speeds advised by some of the armchair hunters and related people, I want you to ask yourself something.
Do you really need to know how fast your slingshot projectile travels? Does owning a chronograph guarantee that you will harvest smallgame by knowing how fast your projectile travels? After all when great grandfather and grandfather or father made their slingshots in the days of the red innertubes and chained rubberband bands and big rubberband days they did not own a digital chronograph. Yet they did take their share of smallgame with a slingshot, in reality the true question then is how and why does a slingshot kill?
I suggest a review of my blog post The Slingshot as a Projectile Weapon to help you understand the killing mechanism by which the slingshot functions, by knowing this you will understand that knowing projectile speed is more of an idle curiosity than a medium of information to guarantee a slingshot's capability of harvesting smallgame.

I have always known over the years even from times when I did not know what a "digital chronograph" was that I did not need to know how fast a slingshot had to be for the sake of hunting. Some of the means by which we tested our slingshots the soup can test are outlined in the link to my other post in this blog post here The Slingshot as a Projectile Weapon.

The old timers who used the old style slingshot elastics did not have these problems, this I think is the problem we face in our modern age with the information super highway the internet, too many ideas to stay focused on what one truly needs to know about any given subject. Life has become too lazy and non dependant on personal experience, nor is it common for people to visit the local library and do their own research a sad affair. Most of my early education was gained in the Los Angeles County Library system, we should all support our local libraries they are a fading treasure.

Exaggerated Projectile Velocity claims

Often when an aspiring slingshot style hunter visits one of the big forums about Slingshots they will visit their "hunting section" and ask the question what kind of elastic and what kind of weight/grains steel or lead ball projectile is effective for hunting.  The answers fall along these similar lines and believe me these are no exaggerations as I have seen these over estimated recommendations parroted many times. 

(FPS = feet per second)
44 cal lead ball at 250 minimum
36 cal lead ball at 300 fps
 7/16 steel ball bearing at 300 fps
1/2 inch steel at over 200 fps
.50 cal lead ball at 200 fps minimum

Aside from this these would be hunters or arm chair hunters as I like to call these people will also lecture you on things they know little about such as elastic pull weight. By the end of the arm chair hunter's lecture the poor aspiring slingshot style hunter leaves the session scratching his head and regretting even asking the advice of these moderators in these big forums.

Am I attacking these pseudo experts? Of course not, this blog is intended to share the truth and nothing more. Now let's see the mythbusting facts vs the above exaggerated claims.

Real world field proven slingshot projectile velocities with projectile weight, speed and game harvested.

Most of what follows are experiences my own and one is quoted from a friend of mine who is an avid grey squirrel hunter who uses flatbands with a short draw.

What is the basic lethal projectile speed required for hunting smallgame with a slingshot?

Note: When I say basic projectile speed this is not meant as an absolute requirement but a real world observation of what projectile speeds have been field proven to take smallgame.

100 MPH One hundred miles per hour in feet per second translates to  146.6 feet per second.

A .457 lead ball at 140 grains traveling 146 fps will kill a grey squirrel if it is struck in the vital area. I have a friend who hunts with flat bands and his style is different in that he has a very short draw and release and with this velocity he has been able to harvest a grey squirrel one of the toughest of smallgame to harvest with a slingshot. Ironically a 300 grain projectile traveling at 130 fps will do more damage than this smaller projectile. Heavier projectiles can deliver greater impact at a slower speed.

A 300 grain or 20 gram pebble/river stone or rock for that matter traveling at this same 100 MPH is lethal to game larger than even a grey squirrel as it's weight is greater we can expect a greater blunt force on impact. Most of my chronograph field documented results have been using the chained office rubberband elastics and to this I will share what I know to be fact.

Ok then let's break this down into a simple real world chart with some short examples. 

The following is broken down into categories based on types of projectiles I have personally used in the field to bring home some smallgame.

River rocks aka pebbles: A pebble weighing 18 to 22 grams traveling from 146 to 150 fps has been proven effective at taking rabbits and jackrabbits out to 20 + yards. In some instances with the either the errant shot or the animal's natural evasive movement where my shot hit the body either ribs or spine this speed and weight of projectile had enough blunt force to stop the creature and obvious a needed quick finish. In other instances the solid impact produced an instant kill. Even a pebble of this weight will still effectively kill smallgame with a mere speed of 138 fps. As noted a pebble of this weight traveling 100 MPH has a crippling impact.

Lead Balls .50 caliber or (.500): A .50 cal lead ball when cast from scrounged wheel weights weighs approximately 180 grains and when cast from pure lead weighs 188 grains. A .50 cal lead ball of either alloy traveling from 150 to 170 fps will kill smallgame up to large jackrabbits.

 Here's my explanation: 

Although I have limited experience in hunting with lead balls I will share some of my experiences in the field. At one time a personal friend donated for me a mixed bag of hand cast lead balls, among these were various .50 cal lead balls he cast from wheel weights. Having gave these the soup can test I felt they were adequate. At one time I decided to take these .50 cal lead balls on my hunts and designated these for shots past 25 yards since pebbles at that range have more drop and so if you miss the first shot will spook game. I had my opportunity in early 2012 when hunting an abandoned defunct railroad with my dog, I came accross a jackrabbit which from 50 yards away looked smaller than it really was. Having hunted all week with smaller targets in mind I was intending for a head shot and I moved off the gravel railroad and unto the grass and stalked to within 33 to 35 yards. 

The Desert Hare was catching the last rays of the afternoon sun at 40 degrees F so I took my first shot with my alambre resortera armed with chained #64 office rubberbands. The first lead ball sailed over it's head and I took a deep breath drew back as far as I could and let fly the second .50 cal lead ball. A half second later I could hear the impact of the .50 cal projectile as it hit the top of the jackrabbit's head with a loud "pop" similar to a baseball hit by a bat. That was the end the jackrabbit fell to never get up with just it's nerves twitching. The creature was massive and weighed within 8 to 10 lbs and far to big to fit in my usual game bags. The image of this large jackrabbit can be seen at my post
The Slingshot as a Projectile Weapon

How fast was the .50 cal lead ball traveling that took this large jackrabbit? 

I later tested the exact same #64 chained bands that I used on this hunt with my F-1 chronograph and the same batch of .50 cal lead balls. 

The lethal speed of this projectile was a mere 163 fps and no where near the speeds preached by the arm chair hunters out there. This is all fact and not theory this is the point of this blog post. So you see a mere 160 fps can carry enough energy past 100 feet to make such a significant smallgame kill.

I have also taken large pigeon with these .50 cal lead balls and same elastic and speeds with a crop shot which stopped the large pigeon in it's tracks.

But does using a faster slingshot projecting a .50 cal lead ball at 190 to 200 fps give you an advantage you ask? Simple answer.. No: My use of the red chained bands the High Quality #32 rubberbands in a 4x4x4 chain taught me this fact.

The High quality Red #32 rubberband chains in a 4x4x4 chain project the .50 cal lead ball from 193 to 200 fps and I have tried to use these faster rubberbands in similar field situations and found that the shots drop sooner or even curve in flight. Yes a perfect sphere can curve in flight and there is a YT vid of a prominent German shooter showing a "steel ball" curve in flight.

Although another topic all together, I will only say that the faster elastic with same projectile will work better or more accurate within the 20 yard max range but better in 10 to 15 yards. This has been my personal experience and to make these faster elastics perform better you would have to shoot a heavier projectile. This of course is another topic all together and I digress. 

Let's  move to the next most popularly advised slingshot projectile for smallgame hunting. 

Half inch steel ballbearings: To my metric inclined friends across the pond these are 12.7 mm steel balls or .50 cal steel  these 1/2 inch steel balls weigh 129.63 grains around the weight of a .44 cal lead ball cast in wheel weight alloy or slightly more. I believe the .445 lead ball cast in wheel weight alloy is 128 grains.  A half inch steel ball bearing traveling from 167 to 172 fps has enough force to take pigeons and their cousins in the squab family out to 30 yards on several occasions I have taken pigeons with head and neck shots out past 20 yards and the 12.7 mm steelie had enough force to take down the pigeons with a clean kill and crippling if not a perfect shot. One smaller member of the squab family I stopped at 30 yards with one of these half inch steel balls. Yes you can also kill rabbits with these steel balls, please only shoot for the head on rabbits and with pigeons the same head, neck shots for best results.

As you can see these projectile speeds are no where near the exaggerated velocities suggested by the arm chair hunters and their cousins the card & milk jug shooters.

These are just of the in the field results and the resulting chronograph tests I have taken after these smallgame kills. Why did I chronograph after the kills?
Simple I suspected that the projectile velocity was no where near as fast as some of the exaggerated claims seen on the forums out there and I was correct.

I hope this helps the new comer to hunting with a slingshot, to avoid further confusion and no you dont need to chrony your shots beforehand.

Just some food for thought and if you have an questions please feel free to ask.