Ideal calibre for (subsonic) culling?

[Ds J]

Hi Folks, which calibre/s would you recommend for culling on an eco estate? (Apologies if I have asked this before).

At times, subsonic shots out to 25m would be a requirement, and no shots over 100m. Shooting could also occur at night with appropriate lights etc.

Target species: antilope up to kudu and BlueWB.

[Againstthegrains]

A lot depends on what you have available, and what you can adapt for sub-sonic shooting. The easiest is .22LR as most people have one, and you can buy ammo over the shelf. At 25m max you should be ok, as long as you can place that bullet with pin point accuracy.

Remember sub sonic is very low energy, so a 200gr 308 sub sonic has less energy than a 40gr 22 cal bullet going at 2800ft/sec. A bigger caliber is less of a win than speed. Essentially the formula for energy is the mass x speed squared, so the bullet speed is has an exponential relationship with energy, or to put it simply. Speed kills.

[Ds J]

This would mean a .45 caliber bullet at 900fps would be ideal, simply because it covers a larger area.

For longer shots, a properly silenced rifle would obviously do much better.

[BBCT]

I can remember reading many years ago in Magnum Magazine about a similar requirement and the shooter used a 9x57 Mauser (It is a real calibre) and suppressor loaded with handgun bullets. They were apparently much more effective than .22LR

A bolt action 44 Magnum with suppressor would also work well. (Yes they do exist and/or can be built using a Lee-Enfield action because 303 has almost same rim as 44 Magnum)

.300 Blackout?

Most subsonic options will have a trajectory close to a .22LR

As stated by Againsthegrain, much depends on what you have available.

[Treeman]

You want to use the biggest calibre in least necked down case. Straight walls or minimum necked down cases with the biggest hole maker you can find. Simple way of putting it.
I have not yet tried the .303 in subsonic mode, but I know it will work, 308, .458 and .357 lever are all easy sub sonic calibres.
I believe that full wad cutter bullets (if existing) would be the ideal bullet, big flat tissue crushing non deforming bullet. Remember, BC means nothing when shooting at hunting sub sonic ranges.
Some day I will make some .303 220 gr sub sonic ammo using bullets loaded backwards.

[Ds J]

I shot a young wounded kudu a short while ago with my 9mm pistol, and saw an impala yew with a sore eye a two days ago.

It brought me to thinking again - how would one proceed if one had to cull these animals in a reserve, or where loud gun shots are not ideal?

[Againstthegrains]

I agree with the above, that if you can find a rifle in a pistol caliber .44 or .45 than that is your best bet to reload sub-sonic, as the loading is easier/less dangerous than a marginally filled hunting rifle case. The wider the diameter of the bullet the better. But again, as I mentioned, a 200gr bullet has 4 times more energy than a 50gr bullet at the same speed. But a 50gr bullet travelling at double the speed will have 4 times more energy, and at 4 times the speed will have 16 times the energy. Basic laws of physics.

Hunting rifle cases are scary when they are partially filled, because the powder column burns very inconsistently, even with fillers. They can also be extremely dangerous, as what can happen is that the primer ignition stirs up the powder, it can burn like  a gas, with all granules igniting simultaneously, or ignites side ways along the full length of the case as the primer flash shoots out above the powder lying flat. This sudden release of gas, as opposed to the column burning through from the primer to the bullet has been know to cause "sub-sonic" hand loads to blow up rifle actions with a fraction of the power of a normal load.

If you have a heavy barreled well silenced small caliber eg 204 or 223 with V-max bullets, then it deadly accurate and super effective, and those little bullets disintegrate on impact, making them safe in built up areas to avoid pass throughs and ricochets. The only thing you hear is the sonic crack which is very little if you shoot at very close distances compared to a 200m shot. Explained as follows:

What Changes Between 10 m and 200 m?
At 10 m, you're mostly hearing:
The muzzle blast, reduced by the suppressor.

A short portion of the bullet's shockwave, because it's only been flying 10 m.

At 200 m, if you're anywhere near the bullet's path:
You're exposed to a longer segment of the bullet's Mach cone — more shockwave hits your ears.

It creates a longer-duration and possibly louder crack, not because the wave got stronger, but because you're intersecting more of it.

[oafpatroll]

A silenced Ruger M77/44 which is a thing I have always lusted after would seem to be just the ticket. It was used as the basis for a reimagined De Lisle carbine called the Silent Destroyer.

[Againstthegrains]

A real world application of the above is as follows: I often visit a farm in an area with small holdings and houses near by. Many of the surrounding residents are city slicker bunny hugger greenies, that are very anti gun. The farmer is happy for me to use my suppressed with Recoil Reaper 204 Ruger (32gr V-max at 4000ft/sec), so long as I am shooting the pigs at near point blank range. They drop like stones with this little bullet, and I've never had a pass through. He prefers this to a .22 sub sonic, as the kills are very clean and quick (brain gets turned to mush). We've never had a chirp from the neighbours. When I offered to pop a pesky vervet on the other side of an open field, he nearly had a heart attack, because of the distance the sonic boom travels.

[janfred]

The whole idea behind OBT is to ignite the powder as fast as possible. And the primer flash through powder ignites far more powder immediately (burns inside out with very little free volume) than a flash over the top of a half filled case (burnig top down with large free volume).

Also, that is why subsonic loads in rifle cartriges are done with fast pistol powder. Every granule is ignited even before the bullet has fully left the case.