Ricochet injury at 50 feet

[bennedose]

I have a 50 foot air rifle plinking range in my backyard which is set up to prevent pellets from straying harmfully. There are walls on two sides and an overhanging corrugated steel sheet above to stop stray pellets that go upwards and out into a neighbor's backyard. The wall behind the targets has a steel plate covered by two layers of cloth. Having used this range for shooting over 2000 pellets, I have found that most land on the ground within 10 feet, or embed themselves in the pellet catcher. But once in a while I have had a ricochet coming off the tin can target itself and land near my feet - mostly at 30 to 40 feet away. I always wear eye protection.

This morning I was shooting at the concave base of an already punctured, empty aerosol can because it offered a challenging target at 50 feet. I was shooting a Precihole Orion and after one shot I saw the target jump followed by a stinging sensation on my right shin. I found a minor injury on my leg from the ricochet (photo below)

The injury is trivial, but if it had been the eye of a pet or someone squatting or sitting near ground level, it could have been serious. I cannot overemphasize the importance of not "shooting across" someone who is out of the way but closer to the target.

Lesson for me. I will never again shoot at the concave base of such cans because they are more difficult to punture and may actually "focus" the ricochet back at the shooter. The pellet had dropped 5 feet by the time it hit me and from that it is easy to calculate that it hit me at about 90 fps or just over 60 mph (about 100 kmph). Enough to puncture skin

Image of minor wound on shin
https://docs.google.com/file/d/0B3JNY4I ... sp=sharing

Image of target
https://docs.google.com/file/d/0B3JNY4I ... sp=sharing

[TwoRivers]

I don't think you can calculate velocity from the drop, the angle of departure from the can bottom being unknown.

[bennedose]

Absolutely right. The calculation is at best a guesstimate.

[brihacharan]

Bennedose wrote:
Lesson for me. I will never again shoot at the concave base of such cans because they are more difficult to puncture and may actually "focus" the ricochet back at the shooter. The pellet had dropped 5 feet by the time it hit me and from that it is easy to calculate that it hit me at about 90 fps or just over 60 mph (about 100 kmph)- enough to puncture skin

Hi bennedose,
Although a minor injury – The prospect of such an event happening is frightening.
I’m a bit curious – Concave surfaces have the lesser propensity to ricochet unlike a convex surface unless you have hit the rim of the container – but then from the images it’s not perceptible!!!
It was fortunate that you were wearing an eye protection!
All this only emphasizes the eminent need to observe SAFETY RULES!
Yes! A lesson well learned!!!
Briha

[bennedose]

I’m a bit curious – Concave surfaces have the lesser propensity to ricochet unlike a convex surface unless you have hit the rim of the container – but then from the images it’s not perceptible!!!

Briha

You know Briha, this statement gave me an idea and made me break my own rule for "research" purposes

It appears that convex surfaces, when not punctured, reflect pellets away in many different directions, and this tendency is potentiated by the falling/tilting/toppling of a can. But concave surfaces tend to reflect back in the approximate path of incidence of pellet

In the case of the concave base of a deodorant tin it appears that the momentum of the pellet simply causes the can to move back longitudinally along its long axis with not lateral deflection. There does seem to be a tendency to bounce the pellet back at the shooter. This morning I did it again as part of my "research"

I took three shots at the concave base (the same one mentioned above from 10 meters. The third one came back and hit me in the belly. I was wearing three layers of clothing (chilly Bangalore morning) so I was stung but not injured.

No more shooting at concave surfaces. I post this as a caution to other plinkers who might be tempted.

[skeetshot]

I would suggest you modify your backstop by hanging some heavy drapery across it.
Any pellet which penetrates the cloth will be stopped by it if it rebounds on the hard backstop behind it.

[essdee1972]

My 2 paise...............

Due to the manufacturing process used for these cans (cold extrusion), the base and the edges of the base are thicker than the sides, hence tend to resist penetration more. Also, unless you hit at the very, exact centre of the concave base (I doubt how many shooters can actually do that - hit a circle a couple of mm diameter!!), you get the pellet hitting the metal at an angle (same with convex bases, also). Hitting at an angle, the force of the pellet reduces by some trigonometric sine-cosine factor. Hence the chances of a ricochet or bounce-back increases.

Moreover, the aerosol cans are under a very high pressure, and need to be substantially stronger than the beer / coke cans. Even for cans hit standing (on the cylindrical "sides"), I have experienced dents when the pellet has sort of "glanced off" or "scratched" the surface and not penetrated (bad aim, yeah!). In coke/beer cans, this "glance" actually tears the aluminium, whereas with aerosol cans, the tear is minimum, and mostly I get a dent.

Bennedose, your experience, bad though it was, would have helped many like me to decide NOT to shoot at the base of a can. Thanks, and hope your injury has healed by now.

[brihacharan]

I’m a bit curious – Concave surfaces have the lesser propensity to ricochet unlike a convex surface unless you have hit the rim of the container – but then from the images it’s not perceptible!!!

Briha

You know Briha, this statement gave me an idea and made me break my own rule for "research" purposes

It appears that convex surfaces, when not punctured, reflect pellets away in many different directions, and this tendency is potentiated by the falling/tilting/toppling of a can. But concave surfaces tend to reflect back in the approximate path of incidence of pellet

In the case of the concave base of a deodorant tin it appears that the momentum of the pellet simply causes the can to move back longitudinally along its long axis with not lateral deflection. There does seem to be a tendency to bounce the pellet back at the shooter. This morning I did it again as part of my "research"

I took three shots at the concave base (the same one mentioned above from 10 meters. The third one came back and hit me in the belly. I was wearing three layers of clothing (chilly Bangalore morning) so I was stung but not injured.

No more shooting at concave surfaces. I post this as a caution to other plinkers who might be tempted.

No more shooting at concave surfaces.
Hope this message gets across to plinkers everywhere!
Would suggest you make a "Pellet Trap" to do all your target practicing henceforth - I use a 5ply corrugated box (which holds 12 beer bottles) - with a 1/4" metal plate at the rear & in front of it stuffed with 2 layers of 4" thick foam rubber + one week old newspapers in front of it.
At 30ft the pellets don't go beyond the 2nd layer of foam!
Briha

[brihacharan]

Hi Guys,
I came across this interesting piece of information regarding pellets which I wish to share...
Composition of Pellets
By Robert Beeman
www.beeman.net/airgunprojectiles.htm

Almost all air-gun pellets mainly are made of soft lead. No other material seems to offer such an excellent combination of weight and density, workability, rifling engagement, air-seal, inertia, expansion upon impact, and resistance to ricochet.

Small amounts of antimony and/or tin are sometimes alloyed into pellet lead to increase its hardness. Harder pellets resist handling and loading damage better, but they also may resist proper engagement by the rifling, and reduce velocity through increased friction and air blow-by. Penetration is increased, but expansion is reduced. A hard pellet may appear more effective in tests because of its greater penetration, but would be less effective than an expanding pellet.

A typical analysis on pellet lead is of the British Standard No. 602: 1956 II:
1.Lead - not less than 99.25% and not more than 99.80%
2.Antimony - not more than 0.10%
3.Zinc - not more than 0.005%
4.Copper - not more than 0.07%
5.Tin - not more than 0.50%;
6.Other elements - not more than 0.075%.

BEEMAN / H&N pellets are 99.9% lead and 0.05% antimony. The addition of antimony has three purposes:

1.To improve the Swaging process.
2.To protect the pellets against transportation damages.
3.To improve resistance to corrosion.
Briha

[bennedose]

I would suggest you modify your backstop by hanging some heavy drapery across it.
Any pellet which penetrates the cloth will be stopped by it if it rebounds on the hard backstop behind it.

In fact my backstop has a double layer of cloth - after I discovered long ago that unless I placed a metal sheet of a sufficiently wide area for bad misses, using a thick compressed particle board backstop only causes vicious ricochets. Wood as a backstop is bad , if the pellet does not embed itself the springiness of dense wood causes a ricochet.But whatever one uses, adding layers of cloth is very good advice. The ricochets I had on here were off the target itself.

[bennedose]

Hitting at an angle, the force of the pellet reduces by some trigonometric sine-cosine factor. Hence the chances of a ricochet or bounce-back increases.

I love the description. Yes that is what seems to have happened. For flat metal plates the pellets generally simply flatten themselves and lose energy. But the concave surface off center simply seems to cause the pellet to slide along the curve across the center and be thrown back at the shooter like a skateboarder going backwards off a ramp.

No more shooting at concave surfaces.
Hope this message gets across to plinkers everywhere!
Would suggest you make a "Pellet Trap" to do all your target practicing henceforth - I use a 5ply corrugated box (which holds 12 beer bottles) - with a 1/4" metal plate at the rear & in front of it stuffed with 2 layers of 4" thick foam rubber + one week old newspapers in front of it.
At 30ft the pellets don't go beyond the 2nd layer of foam!
Briha