Debate about impact - .22 VS .177

[Tramo]

Shot by the same spring/cylinder/piston, the same length barrel, and the same stock.

Will one, a .22 pellet or a .177 pellet hit the target with different impact ( knock down power ) as we like to call it.

Same exact energy spent to propel the pellet = same impact energy.

What's the truth ?
What's YOUR theory ?

.22 out of a RWS 48 won't even penetrate a ground hogs' thick skin at 50 yards.
.177 goes in, won't knock him down but he'll bleed to death in his den - internal if not external.

I would love to hear from all who regularly shoot both calibers.

Bring on the discussion/debate.

[Onebaddj]

My 22 350 shooting 14.6 gr pellets puts ojt more fpe at 28 yds than my 177 350 or 470 do point blank.

[rsterne]

First of all, you have to examine the idea that the same energy spent will produce the same results.... Unfortunately, it won't.... First let's look at what happens inside the gun.... be it Springer, CO2, or whatever....  

The .177 cal has an bore area of 0.0246 sq.in.... The .22 cal (actually 0.217") has a bore area of 0.370 sq.in.... 50% larger.... Since the force available to accelerate the pellet is proportional to the area, there is 50% more force available to accelerate the larger pellet.... Two identically proportioned pellets would vary in weight by the cube of the caliber.... ie if a 7.8 gr. pellet in .177 is scaled up to .22 cal (0.217") it would weigh 84% more which is 14.4 gr... Now we have an 84% heavier pellet being accelerated by a 50% greater force.... That should result in a velocity (in the same barrel length) for the larger pellet of 1.50 / 1.84 = 0.815 times the velocity of the smaller pellet.... If we take a typical springer like a Diana 34 which shoots a 7.8 gr. pellet at 850 fps, we would expect the .22 cal version of the same gun to shoot a 14.4 gr. pellet at 693 fps.... Don't you love it when theory and practice agree?....

It is this mathematical relationship that gives a .22 cal gun the ability to deliver more energy than a .177 cal gun with the same power plant.... Using the example of the Diana 34, in .177 cal the energy is 12.5 FPE.... whereas in .22 cal the energy is 15.4 FPE.... If you have been wondering why the .22 cal version of a given gun always seems to have the edge over the .177 version.... now you know why....

Now let's shift to what happens to the pellet after it leaves the barrel.... This has everything to do with the Ballistics Coefficient and you may have heard that typically .22 cal are better for "bucking the wind".... Is there anything to that claim?.... Let's go back again to the two pellets used in the example above.... The Ballistics Coefficient is the Sectional Density divided by a "Form Factor".... We used two pellets of identical shapes, so the form factors are the same.... The Sectional Density is a measure of how heavy the pellet is for a given caliber.... It is the pellet weight in lbs. divided by the bore squared.... For the 7.8 gr. .177 pellet the SD is (7.8 / (7000x0.177x0.177) = 0.0356.... while for the 14.4 gr. .22 cal pellet the SD is ( 14.4 / (7000x0.217x0.217) = 0.0437.... which is again, 23% more.... The .22 cal pellet should, in theory, have a BC which is 23% better than the identical shape would have in .177 cal.... Another advantage to the larger pellet.... Not only does it leave the muzzle with more energy.... it retains that energy better downrange as well....

Have you ever heard the term "Momentum" used referring to the "Hitting Power" or "Knockdown Power" of a bullet/pellet?.... Whereas the energy (FPE) is proportional to the square of the velocity.... the momentum is simply the velocity times mass.... If you have two pellets with identical energy, the heavier one will have more momentum.... Let's exaggerate to make it easier to understand.... by comparing two pellets of identical energy, but one is 4 times heavier than the other.... The heavier one will be travelling half the speed since the energies are equal.... but it will have twice the momentum....

10 gr. pellet at 1000 fps = 22.2 FPE.... The momentum is (10x1000) / (7000X32) = 0.0446 lbf-s
40 gr. pellet at 500 fps = 22.2 FPE (same).... However the momentum is (40x500) / (7000x32) = 0.0892 lbf-s (twice as much)

Using our pellets from the example above.... the 7.8 gr. pellet at 850 fps is 12.5 FPE and the momentum is 0.0296 lbf-s.... while the 14.4 gr. pellet at 693 fps is 15.4 FPE and the momentum is 0.0446 lbf-s.... which is 50% greater.... That means that the .22 cal pellet, fired from the same gun, will "hit" 50% harder than the .177 pellet.... If you were firing at a pendulum which "absorbed" the impact, the larger caliber would swing the pendulum 50% further....

Since this thread doesn't address trajectory but only "impact".... I think you can see which camp I'm in.... 

Bob

[amb5500c]

What Bob said. There, lets see ya debate that. LOL.
Richard

[oldpink]

A nice scholarly explanation, Bob.
I also wanted to let the OP know that wounding an animal, allowing it to escape into its den, to die a slow, painful death later, is not the kind of "hunting" that an ethical person would intentionally do.
That kind of thing is bound to happen occasionally, because of muffed shots or a particularly tough g-hog, but it's not the sort of thing to feel good about.
My suggestion would be to bring your shooting distance within 35 yards, but I can tell you that the RWS 48 can do the job on a g-hog at 50 yards, just as long as you a) use a suitable pellet, and b) restrict your shots to the "fusebox," brain shot by striking between the eye and the ear.

By proper pellet, I'm talking about either a domed or pointed pellet of suitable weight, preferably 15 grains and up.
Some good choices would be the JSB Exact Jumbo 15.8 grain, JSB Heavy, H&N Baracuda (aka Beeman Kodiak), and the mighty Predator Polymag.

[rijo joseph]

very informative "rsterne"

[Onebaddj]

Thank you professor!

To break it down barney style. Bigger bullet going barely slower makes more wizz bang giving you more pop on target! 

[Tramo]

PERFECT !!!  Great explanation 'rstern' for "lab" measurement in a "vacuum". Taking into account the slowing forces of "gravity" and "wind resistance" both also being 1.5 times on the larger pellet - are the results the same

In my experience, after owning both an RWS 48 in .22 and .177, I know which one (seemed) to have more energy at impact - maybe not right in front of you, but at a distance. One cannot always get right up next to a varmint like he can a target, and accuracy counts too.

One thing for sure - I love to learn from people who can back what they say with science....

Just so you know - I shoot the varmints with a powder 17 HMR, and they don't take three steps let alone go suffer.

Thank you for the replies - keep 'em coming

[Mark 611]

rs good teaching, Tramo I have no problems taking G-Hogs at ranges of 85yds with my spring guns and the 48 in 22cal should have enough power to do the same but I only take head shots! body shots will take them down but as you have found out they'll run back to their den  :- so I never make those kinds of shots, because its either a clean kill or a miss! and the power of the 48 assuming yours is up to snuff around the 800fps range with a 14.3gr pellet you should get a clean pass thru with a head shot out to 75yds easily  

[Toolmaker]

 Bob, that was a GREAT post! Thank you!

[RatRacer]

Excellent explaination!
Saved for posterities sake.

[RedFeather]

Look up Perfesser Taylor's Knock Out formula aka "TKO".  He developed it at the University of Serengeti.  I've applied it to air guns and it seems to hold up.

Don't discount pellet hardness, either.  There have been reports, here and elsewhere, of seemingly sure, point-blank shots failing miserably because the ammo was a dead-soft wadcutter.  Negligible penetration and insufficient transferred shock.  And the game is important, too.  A bird at fifty yards likely won't know the difference between a .177 or .22 since both might be pass-through shots.  In these cases, it's mostly wound channel in a relatively small body.  Either size hole works.

[rash_powder]

Gravity doesn't really come into any of the energy formulas.  the only role gravity has is in the trajectory.  wind resistance or drag is an issue, but that is taken care of, if I understand all this correctly, with the ballistic coefficient. 

as far as wind drift is concerned, in objects of identical shape and differing mass, the heavier object will require a larger amount of energy applied (stronger wind) to change its course due to its larger inertia. 

[Brewerja]

Well, the .22 will transfer much more energy and more SHOCK value to its target, and in a game where the transfer of energy, to effectively disable the target, 22's and larger are king. Im in favor of the .22 due to its energy retaining properties, superior ballistic coefficients, availability of ammo (over the .25) and marginal differences in velocity putting it as the best small game candidate between the .177 and the .25cal,.... heck, i shoot the 18.1gr JSB jumbo heavies with my npxl, and i always see a complete pass through under 50 yards. Besides, at 25yds, i can shoot 4 or 5 of those pellets through the same hole. My vote is always for a 22 or bigger, because airguns dont usually kill by blunt force trauma and or hydrostatic shock value like high powered rifles, airguns kill by producing a wound channel or a wound cavity to destroy vital tissues, essential for the life of the critter. 22's have the potential to carve out more tissue and destroy more area if they fragment (hollow points/poly-mags)

[Mark 611]

Agreed!

[rsterne]

"Gravity" affects only the trajectory.... The variables there are Velocity and Ballistics Coefficient (and angle if you are shooting uphill/downhill).... If you were shooting in a vacuum, then only the velocity would matter.... Since we're not, the BC is important because the pellet slows due to wind resistance....

"Wind Resistance" is determined by the BC.... A .22 cal pellet of identical shape to a .177 pellet will have a BETTER BC because although it is 50% bigger in cross section, it weighs 84% more.... The Sectional Density is higher, the shape (form factor) is the same so the BC is higher.... At the same velocity the larger pellet will have less drop, and less velocity and energy loss....

"Wind Drift" is probably the least understood and most argued part of external ballistics.... The amount of wind drift (ie the amount the pellet drifts sideways due to a crosswind).... is determined ONLY by the DIFFERENCE in the flight time to the target under actual conditions compared to what would have occurred in a vacuum.... The variables are the wind speed and direction, distance to the target, Velocity, and Ballistics Coefficient.... Since for any valid comparison, the wind speed and direction and the distance to target are the same.... we are left with Velocity and BC.... For two pellets of identical BC, the one starting out faster will drift less because the time difference is less.... For two pellets starting at identical velocity, the one with the better BC will drift less.... again because the time difference is less.... Of these two factors, the BC is by FAR the most important....

Let's look at our previous example, using Chairgun to do the wind drift calculations for us.... Let's assign a BC of 0.020 to the .177 pellet.... Using our previous calculations, the .22 cal pellet should have a BC 23% better.... which is 0.020x1.23 = 0.0246.... Let's use a 10 mph crosswind and the target at 50 yards.... Here are the results....

.177 cal; 7.8 gr; 850 fps; BC 0.020 - At 50 yards, V = 621 fps, E = 6.69 FPE, Drift = 5.41"
.22 cal; 14.4 gr; 693 fps; BC= 0.0246 - At 50 yards, V = 537 fps, E = 9.23 FPE, Drift = 5.29"

Note that even though the .22 cal pellet started out at only 693 fps instead of 850 fps.... that it actually had LESS wind drift at 50 yards.... Also note that while the larger pellet only had a 23% advantage in energy at the muzzle.... at 50 yards that advantage has grown to 38% (9.23/6.69 = 1.38)....

Interesting discussion for sure.... The same math can be applied to the advantages of a .25 cal over a .22 cal of course.... and so on.... Aren't we fortunate that we live in a era where .25 cal guns (which were once really a novelty).... now have the power to have a flat trajectory and awesome hitting power.... They currently reign supreme for hunting at 100+ yards....

Bob

[Rocker1]

Professor rsterne, what do you guys think??? lol!!! Thanks for the lesson  David

[Onebaddj]

Rsterne that is alot of math! R u a nuklear sientist! Lol seriously tough good lessons.

Tramo. Ive chronied my guns out to 28 yds. The heavier pellets started out slower but retained more velocity at longer ranges. I actually switched to 10.2 gr jsb's in my 177 cal 350 because at pb they were about .3 fpe behind the 8.4 gr but at 28 yds they lost less than half the velocity of the lighter ones. That gave them more fpe down range. My 22 cal 350 also put out more fpe at 28 yds than both of my 177 mag springers at point blank.

[Tramo]

OK, this is awesome. Bob is REALLY smart and a really good writer/teacher - and I bet it's all from the top of his head, not google.

BUT, I'm REALLY stupid on this subject... and have a need to understand.

We are assuming that the two guns are EXACTLY the same, with exception of the bore, one being .22 and the other .177
If the spring/piston releases exactly the same amount of energy to propel the
two different size pellets, AND the two pellets hit the target with two very different energies.....

WHERE did the extra energy from the smaller pellet go

I remember something about E=MC squared - where E= energy, M=mass, and C= speed of light or something.... but the "extra" energy can't just dis sapear.

[rsterne]

The internal lossses in the gun are likely mostly lost as friction and heat.... The larger caliber is simply more efficient in the way it uses the amount of air compressed.... or in the case of a PCP or CO2 the amount of HPA/CO2 stored in the valve.... More of that energy is changed to kinetic energy instead of being wasted.... Basically none of the potential energy in the gun is lost.... it all changes form.... It's just that in the larger caliber more of it gets converted into kinetic energy of the pellet....

Externally, the larger pellet (of the same shape) retains it's energy better.... ie it loses less to air friction.... The frictional losses would go into kinetic energy or heat (even sound) in the air it passes through....

Bob