Distances for shooting steel targets in canada

[Canuck44]

Thank you for this post. It should be a sticky in it's own right. One is reminded of the following: One experience a thousand times is not a thousand experiences. Too, it is all in the details and science,

Take Care

Bob

 

[Cameron SS]

Thank you for this post. It should be a sticky in it's own right. One is reminded of the following: One experience a thousand times is not a thousand experiences. Too, it is all in the details and science,

Take Care

Bob

One more thing that I didn't mention.

For all the talk of angles, all that obviously goes out the window when you starting shooting at a moving plate. For all their nonsense about shrouds and safe distances, I am surprised that the CFOs have not required target hangers to either be rigid and not allow for steel movement at all, some kind of recoil system that will see the plate come back to rest faster, or alternatively to issue a caution against shooting a moving steel plate. Not that any of those things will make a huge difference, but you would think it would be a logical step if you wanted to add more margins of safety. Its a blessing and curse some times that these CFOs are cops and not engineers.

 

[Suther]

I'm wondering what sort of velocity and range a ricochet from a flat impact on a steel target would have? I'm guessing, but I would think 90 percent of the energy would be lost after striking a steel plate flat on, and that it would only carry a hundred yards further, like it was flung from a slingshot.

Its very hard to predict exactly what will happen. First, it's an inelastic collision so the momentum of the system is conserved, but the kinetic energy of the system is not (part of it is lost to deform the steel and bullet). Second, we can't really predict how many pieces the projectile will split into upon collision, or their respective masses. Third we would need to calculate how much momentum is transferred to the plate. Fourth, we'd have to figure out trajectories for the fragments...

Basically you need a physics degree and lots of precise measuring equipment to get a straight answer, and every shot will behave differently.

10% of the energy of a 9mm is still 35-40ftlbs, which is basically on par with a 29gr 22short w/800 fps muzzle velocity - and I'm not about to volunteer to step infront of that...

 

[Cameron SS]

Its very hard to predict exactly what will happen. First, it's an inelastic collision so the momentum of the system is conserved, but the kinetic energy of the system is not (part of it is lost to deform the steel and bullet). Second, we can't really predict how many pieces the projectile will split into upon collision, or their respective masses. Third we would need to calculate how much momentum is transferred to the plate. Fourth, we'd have to figure out trajectories for the fragments...

Basically you need a physics degree and lots of precise measuring equipment to get a straight answer, and every shot will behave differently.

10% of the energy of a 9mm is still 35-40ftlbs, which is basically on par with a 29gr 22short w/800 fps muzzle velocity - and I'm not about to volunteer to step infront of that...

Maybe I am misunderstanding you, but I think you have momentum and kinetic energy mixed up. Prior to collision the plate is not moving and the bullet is moving very quickly both with forward motion and rotation around its axis of forward travel. After Collision the plate will move, maybe a little, maybe a lot, the bullet will slow considerably or completely drop, and all rotational motion is lost immediately. Virtually all of the momentum factors in the collision system are changed, and not by a trivial amount. At the same time asides from a little bit of friction, all of the KE is still there.

It is not momentum that is transferred to the plate, but KE.

You would not need a degree in physics or anything else to come up with a reasonable approximation of where the fragments would go, the number of fragments, their masses or the distribution of mass among those fragments. You can develop a good reasonable guess either through a very expensive bit of Finite Effects Analysis software, or by firing a hundred rounds under identical circumstances and precisely measuring outcomes. After a hundred shots you should have a pretty good set of data to extrapolate what happened before into what is likely to happen the next time. FEA requires just as much information about what is going on inside the bullet and target material in terms of composition, consistency Modulus and Elastic Limit, as it does on the outside with Energy and Velocity etc.

In either case we would need to know a lot more about the question in order to give an answer.

As for the 9mm, a 124 gr bullet that retained 95% of its mass (worst case after an impact), and had 40 ft lbs of energy would be travelling at approximately 390 FPS, give or take. If fired directly without striking a target this would be comparable to being hit with a direct shot from a range of 1350m +/-. However, as I previously mentioned, the energy in a bullet is not organized the same way before and after an impact. A bullet still rotating on its axis from the rifling is far far more dangerous than a bullet that is tumbling randomly, even with the same mass and speed. A direct hit from a 9 mm at 1300m or a .22 short at PBR are obviously going to cause significant injury. I wouldn't be volunteering to step in front of either one either, but I'd love to see what that tumbling 9 mm round with only 40 ft lbs would do. I suspect it would give you a real good welt, maybe crack a bone, but otherwise would not be life threatening. The effect that the introduction of rifling had on both external and terminal ballistic had was significant.

For the record, a 9 mm round coming off a plate that retained 95% of its mass and is traveling at almost 400 FPS is more what you would expect for a round that just winged a plate and carried on down range, not one what came back up towards the shooter after a bounce. After searching over a hundred you tube videos and blog posts for stories of range ricochets from steel, it seems even with the worst possible set ups and range practice, the only way blood gets drawn is from small cuts from jacket fragments and not the penetration of more substantial lead bullet fragments.

Sureshot gave an example of a small fragment embedding in his neck. I Would love to know more about that fragment, and how it was produced. The odds of such a fragment being produced is already pretty slim. The odds of it coming back towards a shooter even slimmer, at least when you follow basic principles of safe use. I suspect the probability of injury in such events would be measured in the 1 in millions, if not billions.

 

[Suther]

Maybe I am misunderstanding you, but I think you have momentum and kinetic energy mixed up. Prior to collision the plate is not moving and the bullet is moving very quickly both with forward motion and rotation around its axis of forward travel. After Collision the plate will move, maybe a little, maybe a lot, the bullet will slow considerably or completely drop, and all rotational motion is lost immediately. Virtually all of the momentum factors in the collision system are changed, and not by a trivial amount. At the same time asides from a little bit of friction, all of the KE is still there.

It is not momentum that is transferred to the plate, but KE.

You would not need a degree in physics or anything else to come up with a reasonable approximation of where the fragments would go, the number of fragments, their masses or the distribution of mass among those fragments. You can develop a good reasonable guess either through a very expensive bit of Finite Effects Analysis software, or by firing a hundred rounds under identical circumstances and precisely measuring outcomes. After a hundred shots you should have a pretty good set of data to extrapolate what happened before into what is likely to happen the next time. FEA requires just as much information about what is going on inside the bullet and target material in terms of composition, consistency Modulus and Elastic Limit, as it does on the outside with Energy and Velocity etc.

In either case we would need to know a lot more about the question in order to give an answer.

As for the 9mm, a 124 gr bullet that retained 95% of its mass (worst case after an impact), and had 40 ft lbs of energy would be travelling at approximately 390 FPS, give or take. If fired directly without striking a target this would be comparable to being hit with a direct shot from a range of 1350m +/-. However, as I previously mentioned, the energy in a bullet is not organized the same way before and after an impact. A bullet still rotating on its axis from the rifling is far far more dangerous than a bullet that is tumbling randomly, even with the same mass and speed. A direct hit from a 9 mm at 1300m or a .22 short at PBR are obviously going to cause significant injury. I wouldn't be volunteering to step in front of either one either, but I'd love to see what that tumbling 9 mm round with only 40 ft lbs would do. I suspect it would give you a real good welt, maybe crack a bone, but otherwise would not be life threatening. The effect that the introduction of rifling had on both external and terminal ballistic had was significant.

For the record, a 9 mm round coming off a plate that retained 95% of its mass and is traveling at almost 400 FPS is more what you would expect for a round that just winged a plate and carried on down range, not one what came back up towards the shooter after a bounce. After searching over a hundred you tube videos and blog posts for stories of range ricochets from steel, it seems even with the worst possible set ups and range practice, the only way blood gets drawn is from small cuts from jacket fragments and not the penetration of more substantial lead bullet fragments.

Sureshot gave an example of a small fragment embedding in his neck. I Would love to know more about that fragment, and how it was produced. The odds of such a fragment being produced is already pretty slim. The odds of it coming back towards a shooter even slimmer, at least when you follow basic principles of safe use. I suspect the probability of injury in such events would be measured in the 1 in millions, if not billions.

Elastic collisions conserve both momentum and KE. Inelastic only conserve momentum.

This is because in an inelastic collision some energy goes into deformation of the plate and/or bullet. Momentum is never lost in a collision, only transferred from one object to the next. The key is we're talking momentum of the system, not just one part of the system (and in this example the system would be the bullet and the plate, along with the force of gravity and air resistance)

 

[Cameron SS]

Elastic collisions conserve both momentum and KE. Inelastic only conserve momentum.

This is because in an inelastic collision some energy goes into deformation of the plate and/or bullet. Momentum is never lost in a collision, only transferred from one object to the next. The key is we're talking momentum of the system, not just one part of the system (and in this example the system would be the bullet and the plate, along with the force of gravity and air resistance)

I think we are about to really derail here.

I don't think its accurate to suggest that Bullet/Steel collisions are perfectly inelastic. There is certainly an inelastic phase at the precise moment of collision, but its probably best to call it a partially inelastic collision, with some being more partial than others. Some can be quite elastic, while others almost perfectly inelastic. Picture a relatively heavy and slow projectile hitting a soft steel plate where the plate completely caves in and encases the round like a catchers mitt leaving the objects in perfect contact afterwards. This is a nearly perfect inelastic collision, but the objects are in contact more as a result of friction rather than bonding, and there is still SOME KE retained. Same as if the round becomes imbedded, but not fused, in the target material.

Contrast that with a situation where the round nearly perfectly bounces off the plate, or deflects at an extremely oblique angle with virtually no velocity loss.

In theory, when you factor the rotational energy of the bullet being converted from rotational energy into kinetic energy, some collisions could in theory be described as super elastic, but like you said, when you consider the total system, eventually due mostly to gravity, all of the objects in the system will eventually lose all KE and be travelling harmoniously as one object in contact with earth drifting its way through the universe, with relative momentum, and relatively no Kinetic Energy.

But you have to remember that total system also includes people, and at the end of the day, this is the point: Whether a collision is elastic, inelastic or somewhere in between, the momentum and KE of the two objects colliding together relative to each other is only important to our conversation if one of those objects, or a piece of those objects, retains the momentum and more importantly KE necessary to cause harm to a person. Fortunately, in the vast vast majority of all collisions, the result will be safe for anyone wearing glasses and takes basic steps to mitigate risk, already discussed ad nauseam.

 

[Suther]

I think we are about to really derail here.

I don't think its accurate to suggest that Bullet/Steel collisions are perfectly inelastic...

I said nothing about it being perfectly inelastic. If that was the case, we'd have no ricochet and the whole discussion is pointless.

But we're both getting a little too academic here i think. As you mention, and so do others, the risk is low. Not zero obviously, but as long as you use proper ammo, and wear proper safety gear, you are probably at greater risk of harm on the drive to and from the range.

 

[Cameron SS]

But we're both getting a little too academic here i think. As you mention, and so do others, the risk is low. Not zero obviously, but as long as you use proper ammo, and wear proper safety gear, you are probably at greater risk of harm on the drive to and from the range.

Complete agreement on all points. I just wish we could send this to the CFOs who can inject a little bit of science into the rules they impose on range operators.

 

[MRCLARK]

so in other words I,m good for 300 yards in a gravel pit unshrouded?