Pros & Cons of Subsonic Cartridges


The old “never know what hit you” vs. “dead before you hear the bang” argument.

Velocity = energy. 2X velocity = energy**2. No valid argument IMHO.

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Well, yes there is. Increased energy for a subsonic round can be had by increasing the mass of the bullet. But it’s much more efficient to add velocity. With increased mass that generally comes with increased penetration if the flesh is unprotected. There are bullets that will expand at those velocities today but 20+ years ago I didn’t even look, so I assume no expansion for this post.

I played with this extensively a few decades ago with .223. With a subsonic Sierra 80 grain the penetration was some sort of miraculous; 13" through dry hemlock boards and part of that was sideways as the bullet turned itself around. No, that load wouldn’t cycle the gun. For certain jobs silent ammo works fine. Removal of vermin without waking anyone is one of those jobs. With a can and the right action a bullet to the head is hellywood silent not very far away from the shooter. For bagging game for the pot silence can also be an asset under certain conditions. Sometimes one doesn’t care if ones position is known and other times it’s best to stay undetected and under the radar. I settled on a 35gr .22 hornet bullet I bought in bulk as blems for my silent small game load, and it’s good out to 50 yards after which it starts to destabilize and accuracy goes to pot. Since it’s not an exposed lead bullet it can be used through a sealed can with no ill effect.

I have put round after subsonic round into vermin, using NV, IR light, and a can, and they would look around unable to identify where the hurt was coming from, and that was with a silent noise background. So if the gun was at all noisy I would have been made, but I wasn’t.

One negative to subsonic is the rainbow trajectory of the bullet and that will be much the same (terrible) for all subsonic bullets no matter the bullet weight since gravity works on all of them at 32’/sec/sec. They are relatively short range propositions unless one can “grenade launch” the bullets into the target at range.

One positive to supersonic with a can, is the inability of the target to identify the source of the shooter. When the shooter is far enough away for the blast to be silent or muted, the only noise the target hears comes at right angles to the targets ears from the passage of the bullet. That gives the target no clue as to the source of the incoming rounds.

But anyone owning a can knows all of this. I post this info’ for those who don’t yet own any.

OK, enough diarrhea of the keyboard, sorry. I can get carried away.


Thanks for the info!



I am a little confused by your formula.

The one I use, which has been proven correct by ammo maker’s listings of energy and velocity:

Energy (in foot pounds) = Velocity (feet per second) squared, then divided by 450400, then times the grain weight of the bullet.

So, a bullet traveling at 2000 ft per second, and weighing 100 grains, would produce 888 ft. lbs of energy.


Wasn’t so much intended as a formula than a ratio.

Yes, a relatively silent round has value. But a very fast round using the same or similar bullet will have MUCH more energy and get there before the sound. I don’t have much use for a subsonic round. People are shooting in the hills around me all the time. No one cares.