We used to go over this in my physical science classes: Really this boils down to what would you rather have your foot stomped on by? Spike heel or flat heel?Or which way is it easier to drive in a nail? narrow end down or broad. This is a good demonstration of that principle. the small cal has a smaller cross-sectional area (like a spike heel) and since pressure is force divided by area, the pressures will be higher with the slimmer slug. in addition to this, the lower cal pellet would weigh less and be moving faster. Another way to look at this is to make sure you have a power plant that’s up to the task of moving the projectile that you’re planning to use. Bigger isn’t always better.
Not to beat a dead horse, but placement over all else. A miss with a 45-70 is not as deadly as a hit with a .17 hmr. Research Bella Twin.
Isn’t that why we sometimes go with expanding pellets? Basically making big pellets (after contact) out of little pellets?
At equal energy, and depending on the pellet weight chosen, you can prove the same thing with a .22 cal, or even a .177 cal.... IF penetration is your only criteria for being "deadly".... Penetration is proportional to Sectional Density times Impact Velocity.... However, wound channel volume is approximately proportional to FPE.... The choices made in the video (33.9 gr. in .25 cal and 44.7 gr. in .30 cal), both at 70 FPE.... The SD of the 33.9 gr. is 0.077, while that of the 44.7 gr. is 0.071.... At the SAME velocity you would expect about 10% more penetration for the .25 cal.... However, at (almost) equal FPE the velocity of the .25 cal is 966 fps, while that of the .30 cal is 844 fps.... I would expect the relative penetration of the .25 cal to be (0.077 x 966) / (0.071 x 844) = 74.4 / 59.9 = 24% greater than the .30 cal.... The test, as performed at 20 yards, would be unlikely to have exactly the same impact energy, because the pellets are unlikely to lose exactly the same velocity and energy over that distance.... The use of plywood to represent a skull may change the relative remaining energy of the two pellets, but his findings of a difference in penetration of only about 5% in favour of the .25 cal is actually quite a bit lower than what I would expect.... The test without the plywood is inconclusive, as the actual penetration of the .25 cal is just "over 18", so no percentage advantage for the .25 cal is available.... It is an excellent demonstration, and explained well, and the results are as to be expected, given the test criteria....Sectional Density tends to increase with caliber, in fact it is proportional to caliber if the shape is constant.... A .30 cal. roundball, which weighs 40 gr. has a 20% higher SD than a .25 cal roundball, which weighs 23 gr.... If they both impact the quarry at the same velocity, the .30 cal will have about 20% more penetration, and about 70% more FPE (and wound channel volume).... Obviously it requires a more powerful airgun to achieve the same velocity, and hence higher FPE, with the larger caliber.... but there is no question which one, in that case, is "deadlier"....Hollowpoints, which expand, trade off penetration for increased wound channel diameter.... IMO the wound channel VOLUME remains about the same with a HP, however.... but introducing this "variable variable" makes predictions almost impossible, other than in the most general terms.... Statistics are like a Bikini.... What they reveal is enticing, but what they conceal is vital.... Bob
I just posted PART II of this examination as it's own thread if anyone would like to take a look.-Donnie
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