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airbuddy3 · Member

The English Kept it simple .177 for feathers and .22 for fur .

Today we have many more caliber choices , here are some thought on the subject that may help someone choose "the right caliber " for her/his application .

The .177 has less area for the air to Push against .the .22 has 60% more area for the air/gas to push against .
That makes it more efficient ..about 15% more efficient , if you take the same powerplant in .177 lets say you get 900 fps7.9gr for 14.2.pe if you changed the barrel and nothing else to .22 it may get 680fps.22 14.3 gr
for 15.fpe thats 15% Increase just because the powerplant doesnt have to fight the resistance of the skinnier barrel and has more area to push against .

If you take the .22 and .20 comparison for example if we use the same wieght pellets and fire them out of a HW80 ..In .20 it will do 725fps in .22 it will do 750fps same action same pellet wieght the only difference is how much surface area the air can push against . That is a difference of 16.5 fpe and 18fpe just for the difference of caliber .

now penetration works the opposite less surface area = less drag and Higher BC( assumeing the wieght is Constant) and more penetration . so the 725fps .20 cal will penetrate
4 inches into flesh at 45 yds and the .22 at 750 will penetrate 3.3 inches
at the same distance . If both are going to pass through a squirrel or a rabbit at that distance guess which one is IMPARTING more Energy
to the Game . The bigger pellet is , It has much more smack and knockdown power . The bigger surface area ..has A Higher Taylor Knockdown value .
Taylor introduced his formula for knock down values in the 70"s and was used for centerfire effectiveness for big game and police work .
and what its jist is a larger projectile will do a lot more damage than a smaller faster one even if they carried the same energy .

His formula was incorporated in chairgun by Steve of NC ...
and if we run and example

a spring gun shooting 7.9 gr pellets at 900fps will be puting out 14.21fpe
and have a Taylor factor of .159

the same gun in .2o will do 675fps 14.3 for 14.5fpe and A TKF of .239

the same gun in .22 14.3 will do 687 fps for 15fpe and a TKf OF .257

the same gun in .25 would do 566fps 21gr for 15fpe and a TKF of .354

the .25 is 222% of the Knock down of a .177 and 138% of the .22

and the .22 has 161% the knock down of a .177

this would explain why a .50 cal muzzle loader doing 1000fps 182 gr
carrying only 404fpe can have much more of a devastating effect on game than a .223 shooting at 2700fps 55 gr and double the energy at 825fpe .

Food for thought ...

Frank
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AirGunEric · Site Admin

Interesting info, Frank. Poking around through some old notes today? Razz

airbuddy3 · Member

No, Actually a guy on the CAF asked a question about the .177 going 900 Quest , and the phantom in.22 and if its would be worth haveing since they carry approximatly the same power .

so I figured I should share it here also Smile

The outdoorsman · Veteran Member

ummm... interesting post...

.177 for birds and 22 cal for rodents i do not agree with never should a 177 be used for hunting
unless it is very powerful i.e. 800fps

there is no reason that a 22 cant be used for birds and it should be.

as well in some cases a bird is as equaly hard to kill as a "fur" for example a crow and a rabbit require the same velosity or fpe to be killed humainly...