(Rifle Energy) Maybe being thick, but ....

[PPP]

Surely energy being made up of speed and weight is the same energy, by which I mean heavy and slower vs lighter and faster, if they are both delivering say 1900ftlbs, surely that’s the same..

The reason I ask is that my 243 prefers 80gr rather than 100gr but a number of ‘experts’ have. dismissed the 80gr as being too light, even though it delivers more energy..

Surely this is nonsense...?

 

 

 

[Scully]

I dont know what quarry you're shooting, but I've shot Roe and Fox through my .243 with everything from 65grn to 100grn, and nothing I've hit has ever needed a follow up shot or got away. 

[Kalahari]

The heavier rounds carry more energy down range (muzzle energy isn't the whole answer) and in Scotland you have to use 100g round for deer bigger than a Roe. Might have something to do with the comment.

 

David.

[Walker570]

As above.  

[Dougy]

The more energy the better they die. 

[Benthejockey]

My next analogy might be slightly inaccurate but if nothing else it’s simple and might just help grasp it. 

You have a bus, a Ford Focus and a MX5. They’re trundling along at 90mph and get shoved into neutral. They hit a stationary car. The MX5 is vapourised, stopped instantly and doesn’t travel any further. The Ford Focus bends, slows and gradually stops 50 yds away. The damage to the other car is more sustained than being hit by the MX5. Finally the bus hits the stationary car. It smashes straight through the car and keeps on rolling. They all had the same starting speed but once moving their respective weights took more stopping. 

I shoot both 62g and 100g out of my 243. Unless they’re small foxes the 62g bullets generally go into the chest and vapourise the contents and don’t exit. Conversely the 100g bullets usually exit and have a tendency to leave a fox carcass looking like it’s been hit with an axe. They both kill whatever they hit it just depends on what I grab first. The difference being the 100g are soft point and the 62g are Barnes varmint grenades. 

Ive also found that a 55g Winchester soft point out of my 223 acts more like a hammer on rabbits than the 62g bvg’s out of the 243. The 223 guts them and butchers them whereas the 243 tends to blow them up. 

[PPP]

4 hours ago, Scully said:

I dont know what quarry you're shooting, but I've shot Roe and Fox through my .243 with everything from 65grn to 100grn, and nothing I've hit has ever needed a follow up shot or got away. 

Thanks, I had Roe in mind.... thanks for putting my mind at rest 😀

Edited October 28, 2018 by PPP

[PPP]

3 hours ago, Benthejockey said:

My next analogy might be slightly inaccurate but if nothing else it’s simple and might just help grasp it. 

You have a bus, a Ford Focus and a MX5. They’re trundling along at 90mph and get shoved into neutral. They hit a stationary car. The MX5 is vapourised, stopped instantly and doesn’t travel any further. The Ford Focus bends, slows and gradually stops 50 yds away. The damage to the other car is more sustained than being hit by the MX5. Finally the bus hits the stationary car. It smashes straight through the car and keeps on rolling. They all had the same starting speed but once moving their respective weights took more stopping. 

I shoot both 62g and 100g out of my 243. Unless they’re small foxes the 62g bullets generally go into the chest and vapourise the contents and don’t exit. Conversely the 100g bullets usually exit and have a tendency to leave a fox carcass looking like it’s been hit with an axe. They both kill whatever they hit it just depends on what I grab first. The difference being the 100g are soft point and the 62g are Barnes varmint grenades. 

Ive also found that a 55g Winchester soft point out of my 223 acts more like a hammer on rabbits than the 62g bvg’s out of the 243. The 223 guts them and butchers them whereas the 243 tends to blow them up. 

But what if speeds were different and energy was the same?

[scotslad]

Good question, something i've never thought of before.

I'm sure u could get very anal about energies down range wether 1 bullet carries more energy/slows quicker etc down range, but at normal shooting ranges it shouldn't matter really.

 

Just make sure it is legal for eng wotever the desired energy or speed is for ur quarry

 

But bottom line for wot ur wanting at sensible ranges it shouldn't matter, in scotland plenty of roe are shot with 50grain bullets out of various .22cf's.

All about accuracy and short placement really, if ur not hitting them in the right area it won't matter wot speed/energy it has.

[Dougy]

41 minutes ago, PPP said:

But what if speeds were different and energy was the same?

Its all down to Newton, you can work it out but its my bed time.

Net force x displacement=kinetic energy, knowing the energy you can work back to give the same force by changing the velocity.

Quite simple physics really.  

[neutron619]

12 hours ago, Dougy said:

Its all down to Newton, you can work it out but its my bed time.

Net force x displacement=kinetic energy, knowing the energy you can work back to give the same force by changing the velocity.

Quite simple physics really.  

Although it gets a lot more complicated when you take bullet (projectile) construction into account.

I don't actually like this talk of "force" - it's not the force that kills the quarry so much as the damage done when the force acts on the target to deliver the energy - but even then, talking about energy (or force) as being the thing that kills and that having more of either kills "better" is a bit of a misunderstanding.

To cover the simple physics:

Kinetic energy is the thing that moving objects have. When they lose all their kinetic energy, they've stopped moving.

A force is what is exerted by an object - in our case, a bullet - colliding with another object - but in the case of a rifle bullet, the force exerted on the target tends to be very small because rifle bullets tend to blast through things rather than bounce. In fact, the major force involved in shooting - say - a fox, is the outward dispacement of flesh and bodily fluids by the bullet as it travels through the animal (although the point force of the front of the bullet overcoming the resistance of the skin is also important!).

If you think that's all a bit fishy, consider the following: the police officer wearing body armour who's shot with a 12 gauge birdshot cartridge at short range generally gets propelled backwards 1-2 feet from the force of the blast but gets up with perhaps a few broken ribs, but otherwise alive. The force there is all delivered in the forward direction (from the shooter) and is very large (but without penetration, it's effectively an elastic collision).

On the other hand, the same officer shot with a hunting rifle at the same range ends up with a hole all the way through the armour, the officer and the armour again, with the bullet still disappearing off at 1500fps behind him after it's punched through that lot. The force delivered was in the outward direction, perpendicularly away from the surface of the bullet, to split the armour and the officer in a cross-section-of-a-bullet-and-a-bit area. The bullet then flies on, still retaining much of it's energy - this is a complicated, inelastic collision.

It's not that it doesn't take a large force to tear armour and flesh - it's just that the amount of mass displaced is relatively small (compared to the 90kg officer flying back 1-2 feet in the case of the shotgun) and the force required (and exerted) is therefore much smaller.

The fact that this all sounds so counter-intuitive is one of the reasons that it's not terribly helpful to talk about force with regard to terminal ballistics. We can exert a massive force on our target with a bullet or any other moving projectile, but ultimately we don't want Charlie bouncing 50' backwards from the point of impact and walking off startled, but unharmed - which is what would happen if the resolution of equal and opposite forces happened in a "simple physics" kind of way.

Major trauma to the central nervous system / blood loss is what kills living creatures.

People talk a lot about wanting to "dump all of a bullet's energy into the target" as though that were desirable. I understand what they mean by that, but it's actually a bit of a misunderstanding. Assuming you're not taking shots to destroy the CNS, you basically want as much blood loss as possible, as fast as possible. In that respect, two holes are better than one, since it increases the probability that the creature will bleed out quickly.

Like the bus in the example above, a heavy projectile is useful here, because it's harder to stop (think momentum, not kinetic energy) but really, you want your projectile to deliver some energy - causing internal damage to provoke bleeding - but also retain some weight and energy and pass through the quarry, creating the (second) exit wound from which blood can exit. (The Barnes bullet is the exception to the rule here - they are, I suppose, intended to be so internally damaging that the animal bleeds out into its own cavity, which makes a kind of sense, although one might ask whether this actually prolongs the inevitable beacuse blood pressure can't fall as fast.)

Muzzle energy, bullet weight and calibre taken together are all useful predictors of how bullets might  behave, but a better analogy for the cars above would be for bullet construction. The MX5 is the Varmint Grenade, the Focus is the soft point and the bus is the monolithic solid. Construction is key.

Finally, the energy equation is pretty simple:

E = ½mv²

Use mass (m) in kilograms and scalar velocity (v) in meters per second to calculate energy in Joules. To go back the other way:

v = sqrt(2E / m)

or

m = 2E / v²

Multiply the number of Joules by 0.737562 to calculate energy in foot pounds.

Edited October 29, 2018 by neutron619

[walshie]

You seem to know what you're talking about, but the police officer getting propelled 10-20ft backwards? That's the stuff of movies not real life. Don't you watch mythbusters? 

[Scully]

Just now, walshie said:

You seem to know what you're talking about, but the police officer getting propelled 10-20ft backwards? That's the stuff of movies not real life. Don't you watch mythbusters? 

Exactly my thoughts.....the stuff of Hollywood! 

[Ultrastu]

There is a nice vid on utube of a guy wearing body armour and his mate shoots him with a rifle ? (i think ) at point blank .the guy even stands on one leg to prove that he doesnt fall over let alone get blown backwards. 

[wymberley]

I think perhaps if you understand what is being said, then an element of poetic licence is acceptable in order to emphasise the point.

[neutron619]

46 minutes ago, walshie said:

You seem to know what you're talking about, but the police officer getting propelled 10-20ft backwards? That's the stuff of movies not real life. Don't you watch mythbusters? 

Ja, ok - I was being a bit lazy and didn't bother to work those numbers out - and no, I don't watch Mythbusters. Let me make it up to you by editing the post above and providing the calculations now.

Let's say you've got the 90kg officer and a 36g buckshot cartridge fired into armour. Given conservation of momentum

m1v1 = m2v2

and a muzzle velocity for the cartridge of 420m/s

(0.036 * 420) = (90 * ???)

Rearrange:

(0.036 * 420) / 90 = v2 = 0.168m/s

or the officer having resultant velocity of 16.8cm/s after collision. That's still quite a shove - think how hard you have to push a big man to move him at all - but as you say, can be absorbed by movement / adjustment of the body. I dare say that the element of surprise might be enough to allow that kind of force to knock someone off-balance, if not actually over.

 

Edited October 29, 2018 by neutron619

[Dougy]

So there you go then, that's explained that.

 

 

 

Now what was the question

 

 

Neutron,

 

 

Good post

[PPP]

20 hours ago, scotslad said:

Good question, something i've never thought of before.

I'm sure u could get very anal about energies down range wether 1 bullet carries more energy/slows quicker etc down range, but at normal shooting ranges it shouldn't matter really.

 

Just make sure it is legal for eng wotever the desired energy or speed is for ur quarry

 

But bottom line for wot ur wanting at sensible ranges it shouldn't matter, in scotland plenty of roe are shot with 50grain bullets out of various .22cf's.

All about accuracy and short placement really, if ur not hitting them in the right area it won't matter wot speed/energy it has.

Thanks, that makes sense, my rifle is raggedy holes at 100 yards (even in yesterday’s **** weather) with both Winchester and Federal 80gr and an inch and a half with the 100 gr Winchester and 90gr prvi, I’ll stick to the 80 taking your point about Scotland on board.

Neutron, thank you, cap doffed!

 

[scotslad]

19 hours ago, PPP said:

Thanks, that makes sense, my rifle is raggedy holes at 100 yards (even in yesterday’s **** weather) with both Winchester and Federal 80gr and an inch and a half with the 100 gr Winchester and 90gr prvi, I’ll stick to the 80 taking your point about Scotland on board.

Neutron, thank you, cap doffed!

 

 

Ur doing well to group like that so i'd be sticking to that bullet choice. nd as 1 or 2 said ur bullet design how it expands will also make a massive difference more so the a small % energy/speed difference (again at sensible ranges)

Dunno if u ever shoot or plan to shoot larger deer in scotland (so mibee never an issue) but even a 1 1/2" group isn't too bad, for some fok tha would be an acceptable group anyway. Out to 200 ur still a 3" group and considering larger deer have a bigger kill zone for H/L shots ur still well within sensible capabilities.

Wether a different brand at 100gr would make any difference, but even the actuall difference in bullet size realistically won't make much difference to the deer as long as ur accuracy is there

(there will be a lot of red hinds shot in cotland with 22.250's , even thou shouldn't legally be)

[Dekers]

On ‎28‎/‎10‎/‎2018 at 16:33, PPP said:

Surely energy being made up of speed and weight is the same energy, by which I mean heavy and slower vs lighter and faster, if they are both delivering say 1900ftlbs, surely that’s the same..

The reason I ask is that my 243 prefers 80gr rather than 100gr but a number of ‘experts’ have. dismissed the 80gr as being too light, even though it delivers more energy..

Surely this is nonsense...?

 

 

 

Energy is far from being the only arbiter of terminal effect!

[PPP]

5 hours ago, scotslad said:

 

Ur doing well to group like that so i'd be sticking to that bullet choice. nd as 1 or 2 said ur bullet design how it expands will also make a massive difference more so the a small % energy/speed difference (again at sensible ranges)

Dunno if u ever shoot or plan to shoot larger deer in scotland (so mibee never an issue) but even a 1 1/2" group isn't too bad, for some fok tha would be an acceptable group anyway. Out to 200 ur still a 3" group and considering larger deer have a bigger kill zone for H/L shots ur still well within sensible capabilities.

Wether a different brand at 100gr would make any difference, but even the actuall difference in bullet size realistically won't make much difference to the deer as long as ur accuracy is there

(there will be a lot of red hinds shot in cotland with 22.250's , even thou shouldn't legally be)

Thanks, no plans to head to Scotland yet, but when I do there is a .275 in Italy that is ‘mine’ (left to me) so I’ll be having a chat with FAO and bringing that back.