Subsonic- or at least that is what it says on the ammo box. So, I can use sub-sonic ammunition to hunt and not scare away the herd with the load thundering BANG from my rifle.
Or is it?
Subsonic cartridges do make less noise than full-velocity cartridges, but there is still a BANG.
Keep in mind that the quitter ammo does not have enough OOMF to travel far. However, it does have its rightful place.
What is Subsonic Ammo?
The speed of sound is about 1127 feet per second at sea level. When moving object moves faster than that, and breaks that barrier, it creates an audible shock wave. However, most of the noise comes from the expanding gasses escaping form the rifle’s bore, and not the bullet itself. It is the noise from the escaping gasses that is the main problem.
Subsonic ammo does reduce the bang at the muzzle a little due to lower velocity, it will not make your centre-fire rifle’s BANG go “pew”. It is just one way to minimize the noise.
You can also invest in a silencer, which greatly muffles the sound of the escaping gasses. The best is to use a silencer together with subsonic ammo. This will reduce the sound of gunfire to a “pew” or very close to it.
Performance
Performance is notably reduced when using subsonic.
Is it powerful enough to hunt big game?
Is Subsonic Ammo Powerful Enough to Take Big Game?
A slower bullet has significantly less energy than a faster bullet at the same weight. Remember: MASS X VELOCITY2 =ENERGY
Example: a 55-grain .223 REM bullet produces 1280 foot/pound of energy at muzzle break, at 3250 fps.
If the velocity id reduced to a subsonic 1100 fps, it produces only 1500 foot/pound. So, basically, it almost turns a .223 into a .22LR. So you can see the difference.
The other reason is that the same energy that goes forward, goes backward, so when using subsonic, and the energy is reduced, the rearward energy is also reduced, which may cause semi-auto rifles to fail to cycle.
This is a reason why you hardly see subsonic .223 loads on shelves.
How to compensate for lost energy
More mass will allow you to compensate for less velocity like a bullet with a long, large diameter.
300 BLK subsonic 208-grain A-Max load from Hornady delivers 480 foot-pounds of energy from a carbine’s muzzle.
Because of this long bullet’s great ballistic coefficient of .648, at 500 meters it surpasses the energy of a full-power 55-grain .223 Rem., and nearly triple that of a .45 ACP, but does it with a softer voice.
That is reasonable performance at 5o meters if you hunt medium game, but is good for varmint at longer range where noise may be a problem.
Because the energy is reduced, the recoil is also reduced.
Subsonic Rimfire Loads are Best Balance for Hunting
Subsonic performs the best in rimfire rounds. A standard .22 LR performs at 1200 fps and 140 foot/pound of energy at the muzzle. The typical .22LR round travels at about 1050 fps with 100 foot/pound. It is evident that the noise is almost none, but it does not make a huge difference in performance of the bullet on the target.
Competition shooting with .22 LR
The subsonic .22 LR is more accurate because it displays 37 percent less wind deflection due to the disproportional increase of air resistance near the sound barrier. When you combine the .22LR with a suppressor, it becomes a very quiet small-game rifle.
All major ammunition manufacturers have a subsonic load. A round with velocity reduced to 1050 fps has a decibel level lowered to 68, which is almost half of the normal high-velocity .22LR load. Any .22 Short will produce the same result, if your gun can fire them.
Subsonic Disadvantages
Subsonic rounds may have cycling problems for semi-auto rifles or pistils due to the reduced energy, and hence not enough power to cycle all the way. If you use a single shot bolt- or pump action, you will be fine.
If you do fire a semi-auto and have these problems with subsonic, try Winchester’s M-22 Subsonic .22LR. It fires a 45-grain bullet at 1090 fps and is specifically designed for self-loading (semi-auto) firearms.
Subsonic Accuracy
Generally, heavier bullet in the calibre works best because they retain the subsonic round’s energy better over distance. But, if your rifling twist does not spin the bullet fast enough to stabilise long, heavy bullets at subsonic speeds, a lighter bullet will provide better precision. I suggest you then experiment until you get the heaviest bullet your gun is happy with.
If you semi-auto rifle does not cycle these subsonic rounds by itself, you can still shoot it. All you can do is use it like a straight-pull bolt action rifle and pull the cocking lever back after each shot.
Important Note
It is important to note that bullet trajectory will differ greatly with subsonic ammo. Check your zero and test the Point of Impact out to 100m or more. When that is done, you are good to go.
Adjust Shot Placement for Hunting with Subsonic Ammo
Due to its low impact velocity, subsonic bullets do not expand very well in game. It will help to change the shot placement to hit bone. Aim at the shoulder, halfway up to the body. This will aid in bullet expansion and will destroy both lungs, but meat damage will be minimal due to the lower impact speed. If you miss a little high, you can hit the spine, and missing lower will cause a heart shot.