More lack of understanding, and really bad presumptions being made based on partial information.
Also, I realize this forum is for firearm hunting, not bow hunting. It was just the subsonic aspect that I thought was relevant. But, I can believe that it might not be very relevant, since a subsonic bullet is still going about three times as fast as an arrow.
It's not about bullet vs. arrow velocity either - read my post above again - the arrow gets to the deer long before the deer can react. A bullet gets there faster, but the arrow still gets there fast enough to kill before the reaction. Not being a hunter yourself, I can appreciate your lack of understanding for how hunting is done, but I can assure you, arrows kill deer every season, and deer don't jump out of the way of the shot at ethical ranges. Yes, a deer can take a step and walk out of the way of a bullet at 1,000yrds, or an arrow at 100yrds, but that's why guys don't typically hunt game at those ranges, and those which do, only do so under specific conditions. (Withstanding here, I don't own a bow which could be heard at 100yrds. They're all too quiet).
I understand that an ethical kill is the number one priority, but sometimes the energy of a heavier, slower bullet is equal to that of a lighter, faster bullet, but the latter seems to be more common, though the former would be quieter.
Sound generated by a firearm is largely dictated by the pressure of the cartridge, the powder used, and the overall energy. Even at 900fps, the bullet traveling subsonic, the gases leaving the muzzle will be super sonic, especially those leaving the BC gap of a revolver (since you're now using the 44spcl Critical Defense load as your evidence). There's no guarantee a sub-sonic load, of the same energy, will actually be any quieter than a supersonic load, especially when you're considering a 165grn at 1150fps vs. a 180grn at 1100fps.
Read my first post again - you're letting your mind wander into imaginary land when the math to get your answer is VERY simple. The difference in a time of flight for sound vs. a 1100fps bullet vs. a 1150 bullet is going to be measured in milliseconds - the animal doesn't have a chance to "jump out of the way" of either bullet.
Maybe the flatter trajectory of a lighter, faster bullet is the reason for this, not getting the bullet to the animal before they hear it coming, as I hypothesized.
Most of us hunt with supersonic rounds because we can shoot much farther than we could with subsonic loads. But when you start splitting hairs between an 1100fps load and an 1150, there's really no difference in trajectory. When you get to longer ranges with modern bottleneck cartridges, you can't outrun aerodynamics - which means a lighter, faster bullet doesn't actually shoot flatter than a heavier, slower bullet. Heavier bullets have better ballistic coefficients - they're more aerodynamic - so they retain velocity better. It's like a guy with a lower salary being better with money than someone with a higher salary. The penny pincher starts out with less than the high earner, but he does better keeping it, so he ends up with more money in the long run. Bullets work the same way.
For example, in the case of Hornady Critical Defense .44 Special, we have a 165 grain bullet going 1150 fps (just barely supersonic), equaling 484 ft-lbs of muzzle energy; it seems to me that they could’ve very easily made it a 180 grain bullet going 1100 fps (just barely subsonic), still equaling 484 ft-lbs of muzzle energy - either would potentially provide an ethical kill; arguably, the slower heavier bullet with equal energy would penetrate better on a thicker-skinned animal (or a heavily clothed perpetrator, for that matter) than a lighter, faster bullet, due to a higher sectional density.
It seems like Hornady intentionally made it supersonic. That’s where I got the idea that it was to get the bullet to the target before the sound of the bullet gets to the target.
Hornady made it supersonic because 1150 is as fast as they could push the 165grn bullet they chose to load. I can assure you, "beating the sound to the target" was NOT a consideration of Hornady in designing the Critical Defense 44 SPCL load - that "Critical Defense" part of the name means it's a defensive shooting load, not a hunting load. They wanted a moderate recoil load, so they chose a light bullet.
So learn something here - heavier bullets produce greater recoil. A 180grn bullet at 1100fps will have about 8% greater recoil than a 165grn bullet at 1150fps. (Google appropriate powder loads for these bullets, then google free recoil calculator, if you don't already understand the math).
Now, I think it may be to PREVENT the use of a suppressor
Nope. 1) Nobody is using a suppressor in a 44 Spcl revolver for which the Critical Defense load is designed. 2) Flying supersonic does not preclude or "prevent" the use of a suppressor - guys shoot suppressors on supersonic rounds every day.
just to get a flatter trajectory
Nope - as mentioned above. 1) It's a defensive load, trajectory isn't a major concern. 2) The trajectories of a 1150fps 165grn and a 1100fps 180grn bullet are almost identical at ranges even farther than the designed purpose.
OR, maybe the lighter, faster hollow-point bullet is more likely to fully expand on impact than a heavier, slower bullet. (Though, the Critical Defense .45 ACP is a 185 grain bullet going 1000 fps, so…?)
Nope - not all bullets have the same designed construction. Hornady gets to design their bullets however they choose. If they want a 180grn to expand more or at a lower velocity than a 165grn bullet, they simply design the bullet differently. Weight isn't the only design parameter for a bullet; Jacket thickness, jacket taper, tip fill, bonding, tip segmenting, etc are all aspects which allow the designer to match a bullet weight with a desired expansion velocity. Want a 165grn to pass through a deer? An FMJ or monometal bullet will pass through. Want a 180grn to explode on contact? Give it a super thin jacket, a big polymer tip, and a non-bonded core - it'll tear itself apart and penetrate less than the 165grn FMJ.
