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Penetration vs Power


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I'm not opening the calibre can of worms, its not been that quiet yet.

In the recent FAC thread ultra stu mentioned that the penetration wouldn't be different with more power just a bigger wound channel (correct me if I've got it wrong ?)

The last squirrel i shot was at pretty close range 15 metres max, the shot went between the shoulder blades and came out the ribs, but didn't exit it was just under the skin so I've got the pellet.

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As you can see there is quite a bit of damage but the pellet is still in good shape, the squirrels insides were a mess, but if i had have been shooting at 900 fps ish i certainly wouldn't have expected the pellet to have stayed in the squirrel, quite often get them going through on head shots.

So would you not expect a faster therefore more power pellet to have passed through?

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I can understand both of your view points. To me when a fast projectile hits a target, depending on its core, I'd expect it to expand on impact and make a huge channel after. 

But the otherside of me says why doesn't it just drill a clean hole straight through?

Realisticly every shot is different, every round of a certain density, and every bone, sinew and muscle a backstop to slow a round down. I'd say it's more down to ammo density and type/shape than power/speed. 

Was this helpful. Nope - but with your last question, would I expect a more powerful shot to have gone through? Definitely, as I assume it was a 12ft/lb that did that shot and got that far, if it was laying just under the skin, I reckon another 2ft/lb would of punched through. 

Edited by strimmer_13
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If Stu's statement is correct i.e penetration is not relative to velocity - then can he post a video of himself A/ dropping a pellet on his foot  then B/shooting a pellet into his foot - make sure you use the same weight pellet Stu to avoid any confusion over what exactly caused your trip to A&E.

Edited by bruno22rf
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4 hours ago, strimmer_13 said:

Was this helpful. Nope - but with your last question, would I expect a more powerful shot to have gone through? Definitely, as I assume it was a 12ft/lb that did that shot and got that far, if it was laying just under the skin, I reckon another 2ft/lb would of punched through. 

of course its helpful, everyone has different opinions or thoughts.

and yes 12ft/lb

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Thanks bruno .i knew you would find the flaw in my argument. .

"Pellet penetration of a medium isnt governed primarily by the velocity. " 

What i mean by this is .

Obviuosly  a pellet travelling at 15 fps isnt going to penetrate as deep as a 900 fps pellet. 

But the difference between say a 900 fps and a 600 fps pellet is so small (ie much less than the percentage difference in velocity as to be disgarded as a major factor. ) .

What seems to kept being forgotten in this argument is the density (call it bc if you like ) of the pellet and the medium you shoot into .

 

Pellets are different .some are designed to penetrate others not ..

So a pellet that doesnt deform much . (Heavy round solid slug ) could  penetrate a bit  deeper with a higher impact velocity .A pellet thats designed to expand on impact. Wont penetrate deeper at all with higher velocity .infact penetrate less .

 

A great example of this is a 17 hmr  

They almost explode at close range as the bullet rips its self apart . (Shallow depth .) But at long range (lower velocity ) they penetrate much much deeper .

 

 

 

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What's also VERY important and seems to have been overlooked is pellet weight as well, put simply, a heavier pellet travelling at the same speed as a light pellet will carry more energy!  I see no mention of pellet shape either, another factor to consider.

The OP said forget caliber, well it isn't that simple either!

There is no dodging any parameter here if you want anything close to an accurate answer, and that is without taking into account the variables such as path through quarry!

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Small easy experiment for you .

With a open palm of your hand slap the surface of your bath water as fast as you can .now repeat at a slower speed .can you feel the impact force and resistance of the water being greater on the faster speed .? 

Its the reciprocal force that deforms the projectile (creating a larger head ) and  slows it faster  . 

Problem with rabbits and quarry in general is that the medium (flesh bone etc ) isnt constant so to get any meaningful data is almost impossible  (i know ive tried and tried and gave up ).

So the best we can do is shoot ballistic gel to gauge penetration depth .and clay /wax to get a feel for the reactive wound cavity ..

Go ahead buy some gel (or make it ) 

And then come back to me with a "wow stu you were right all along "  post .

 

 

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11 hours ago, bruno22rf said:

If Stu's statement is correct i.e penetration is not relative to velocity - then can he post a video of himself A/ dropping a pellet on his foot  then B/shooting a pellet into his foot - make sure you use the same weight pellet Stu to avoid any confusion over what exactly caused your trip to A&E.

That just made me chuckle ?

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That's me out Stu - I don't have a bath :hmm:. BTW - I'm happy ( just to be fair to you) for you to only shoot the pellet into your foot at 300 fps as the difference in penetration, apparently, between that velocity and the free falling pellet can be disregarded. You can use your Gel to plug the hole in your foot? 

Edited by bruno22rf
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2 hours ago, Robertt said:

What is interesting is that the above clearly illustrates the fact that at sub 12, JSB's etc behave like solids.

They do not get mashed up like some believe.

Note the rifling marks.

 

I'm afraid it doesn't show that at all!    Assuming 12ft lb in all cases, the state of the pellet will depend on the distance to target/energy it still carries and exactly what it hits, also the metallic/plastic/whatever construction of the pellet.    If a pellet hits nothing but soft tissue it may well come out pretty much unscathed, if it hits dense matter like bone, either directly or a glancing blow the result may well be very different!

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I have not done penetration tests on air pellets but have done a fair few on centre fire rifle bullets and shotgun pellets in a known medium (wet newsprint) and that is where the crunch comes. As said above animals and birds are made up of all sorts of 'materials' and penetration is governed by where the projectile hits. How many barn pigeons have you shot front end on?

I am up to over 300 total on one farm and many of these where front end shots. I would make a guess that 8 out of ten drop like a stone without a flap. Then you have a couple which drop and start walking about. Same gun, same pellet, relatively the same distance but the pellet came across a slightly different 'medium' on the way in which either deflected it or stopped it in it's tracks.  When that pellet, bullet leaves the end of the barrel it is it's own free agent and no amount of careful testing can dictate precisely what it will do on hitting flesh and bone.

Hit an elche(moose) in Sweden at 45yrds with a 350gr RN out of my 458 Win Mag, angled shot in just infron of shoulder. The bullet just scored the lungs and hit the rib on the far side and bounced back across the liver which did most damage and buried itself into the huge stomach contents never to be retrieved.  I think most shooters would have expected that bullet to have blown straight through.  You can never say never, just use the very best projectile for the job.

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I might be being thick but I see a tremendous in penetration with the same pellet at different velocities, .20 premiers shot at 900-940 fps shoot straight through 30mil soft wood at 50yds at 600 fps they are maybe a pellet length or so into the wood . I found very similar differences with jsb/air arms , bisley magnums in .22  with 200/300fps making a real difference . Years back I ran a .177 rapid fac upto 25ftbs it was probably the worst killing airrifle I've owned due to the little pellets zipping through the quarry , I know that terry doe found the same at the time. 

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I bet u used .177 bisley mags in the fac rapid ? 

These are a heavy penetrating round .and as such dont impart a wide wound channel in  any medium .at any velocity

Obviously a bit wider at 900 fps over 600 fps .

But if you had dropped the energy to around 16 fpe and used 8.4 grn .exacts you would have found the opposite .a pellet that drops rabbits with head shots so hard and fast it seems unfair .You basically fell for the whole (more power must be better trap ) .

And a .177 at 25 fpe is about 8 fpe too much .

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7 hours ago, Ultrastu said:

But the difference between say a 900 fps and a 600 fps pellet is so small (ie much less than the percentage difference in velocity as to be disgarded as a major factor. ) .

cheers Stu, that's the bit that had me thinking, using the above figures i find it hard to understand how "any" projectile going 50% faster isn't going to penetrate more.

this was why i said ignore calibre Dekers I'm thinking anything going 50% faster has to be different.

the pellet I've used as an example is a crossman accupell, at 12 ft/lb and i believe they are a different alloy/ harder than a lot of more modern pellets.

45 minutes ago, Whitetail said:

I might be being thick but I see a tremendous in penetration with the same pellet at different velocities, .20 premiers shot at 900-940 fps shoot straight through 30mil soft wood at 50yds at 600 fps they are maybe a pellet length or so into the wood . I found very similar differences with jsb/air arms , bisley magnums in .22  with 200/300fps making a real difference . Years back I ran a .177 rapid fac upto 25ftbs it was probably the worst killing airrifle I've owned due to the little pellets zipping through the quarry , I know that terry doe found the same at the time. 

Cheers this was what i thought would happen.

some good responses to this except Bruno, but i did laugh ? 

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Go on utube and search 

Shooting .22 pellets using nailgun blanks .

I cant do links .

 

This will show how speed effects penetration .

Basically .they load .22 pellets into a .22 lr and fire them with nail blanks .and get velocities around 2800 fps .from a 14 grn pellet .and compare to a standard 40 grn hv .22 lr bullet around 1200 fps .

They shoot a watermelon .and the pellet makes a MASSIVE entry hole and cavity and doesnt go through .the .22lr bullet zips right  through with a diddy little hole  in and out ..

IMG_20180820_151034.jpg

IMG_20180820_151056.jpg

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I dont need to show the image of the .22lr its a small unimpressive hole .

So ok .thats bullet compared to a  pellet .but you get the jist  very fast equals LOWER penetration As the fragile projectile deforms on impact making a wide channel .

This is what happens to flesh .

Im not really bothered about an extra  mm of penetration either way in wood or metal or paper .its irrelevant to hunting .

The water melon .although far from perfect is a lot closer to flesh (being 75 % water ) than wood .

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I can see im gonna have to do these tests all over again .with different cals at different speeds and document them on here ? 

I can shoot .177 from 200 to 900 fps in 100 fps intervals .

And measure penetration depth and wound cavity width .

I can also shoot .22 at 880 fpe and .25 at 880 fps .

So comparing cals .

I can show u the difference between high bc and low bc  pellets in .177 at diffent speeds .

Showing how a high bc will penetrate a touch more with increased velocity .and how a low bc pellet will penetrate  a bit less and how a medium bc pellet will penetrate almost exactly the same irrespective of velocity .. .

Results depend on the medium but again gel and clay are my 2 prefered  ones .for how they show us the effects. 

 

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1 hour ago, bruno22rf said:

That's me out Stu - I don't have a bath :hmm:. BTW - I'm happy ( just to be fair to you) for you to only shoot the pellet into your foot at 300 fps as the difference in penetration, apparently, between that velocity and the free falling pellet can be disregarded. You can use your Gel to plug the hole in your foot? 

The reason why i would suffer more foot damage is because .a free falling pellet is gonna be doing around 1 fps on foot impact but the shot pellet at 300 fps .is 300 % faster.  

The difference between 600 and 900 fps is only and increase in 50 % velocity and even less energy .

This is why there isnt a comparison between the to examples 

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24 minutes ago, Ultrastu said:

I can see im gonna have to do these tests all over again .with different cals at different speeds and document them on here ? 

I can shoot .177 from 200 to 900 fps in 100 fps intervals .

And measure penetration depth and wound cavity width .

I can also shoot .22 at 880 fpe and .25 at 880 fps .

So comparing cals .

I can show u the difference between high bc and low bc  pellets in .177 at diffent speeds .

Showing how a high bc will penetrate a touch more with increased velocity .and how a low bc pellet will penetrate  a bit less and how a medium bc pellet will penetrate almost exactly the same irrespective of velocity .. .

Results depend on the medium but again gel and clay are my 2 prefered  ones .for how they show us the effects. 

 

I for one am looking forward to you experiment :good:. Can't wait to see the result.

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