"I would disagree. With all hunting weapons".
I don't understand what your saying here.
What I was saying is I would not take a animal over 50 yards with a air rifle. And usually much closer. At 50 yards a .177 .22 or .25 has a flat enough trajectory to hunt. The later two deliver more energy.
The bigger and heavier the projectile, the
longer it will retain it's velocity. If the gun has the initial power to get the .25 caliber pellet out to 50 yards it will hit the hardest of the 3.
MY experience with the three is this. My .177 will shoot a tighter group at 25 yds than I get with my .22 cal. But it can be very close. At 40 yds it's a they are the same, at 50yds it is the .22 cal beats the .177.
The .25 performs almost as good as the .22 at 30-40 or 50 yards.
"What I was saying is I would not take a animal over 50 yards with an air rifle" I'm assuming you are referring to only spring powered air rifles here and I would agree. My 14-15 fpe .177 HW97K gives me confidence out to 50ish meters on small game. It will consistently shoot nickel sized groups out to that distance(and better if I'm having a good day)
and I'm sure a .22 could do just as well. Possibly even slightly better depending on the barrel, shooter, conditions, etc. but I feel that this is a tossup at these lower sub 15 fpe power levels.
The point that I’m trying to make is that the
flatter trajectory of the .177 vs a .22 at a given power level(particularly low power springers) results in a
larger margin of error in calculating range and thus holdover. Obviously, this isn’t based on caliber or projectile weight but rather velocity.
For example my PCP shooting slugs at 965 fps has a PBR of 15-55 meters(+\-1 cm). This is fantastic for pesting because I just hold dead on inside of 60 meters and anything past that generally will give me the time to range and dial.
For this reason, my ideal velocity with all three of my springers is around 800 fps. This results in a PBR of approximately 30 meters given a 20 meter zero. For me personally, having a 30 meter PBR is a huge plus when hunting or pesting as it eliminates all calculations and holdovers. Admittedly, my HW30S at 7 fpe is only pushing a 7 grain pellet to about 700 fps and so my PBR for it is slightly south of 30 meters.
Given a 20 meter zero and 11 fpe...a 8 grain .177 pellet has the same amount of drop from 40-50 meters as a 15 grain .22 pellet has from 30-40 meters. Given that 20 meter zero, that same .177 pellet has the exact same POI at 30 meters while the .22 pellet is already an inch low. Past 30 meters with the .22 if you miscalculate the range by more than 2 or 3 meters you risk a poor placed shot or miss.
If your main quarry is paper or steel it's not a big deal...but the targets that I mainly shoot usually try to stay alive.
Clarification, all of this is assuming sub 15 fpe power levels. North of that, I do feel that the .22 starts to gain an edge in effectiveness. And for what it's worth...this is just my $.02.