What’s the best calibre for hunting?

There is a dizzying array of calibres available for the hunter to choose from – Will O’Meara helps cut through the confusion and make the right choice

The first thing to realise is that we all have an emotional investment in the calibre that we own: we made a decision to buy that calibre, it is what we use and we want it to be great.

We must put aside sayings such as “it’s not the calibre – it’s where you put the bullet”, because such sayings fail to take into consideration what happens when things go wrong.

I don’t intend this to be a lecture on what’s the ‘best’ calibre, because each calibre has its place and what suits my needs may not suit yours. What I would like to explore is the merits of some larger chamberings and their suitability for hunting.

When objectively looking at calibre choice I like to initially look at two factors; terminal ballistic performance, and “shootability” (in basic terms, as felt recoil goes up, shootability goes down). With the availability and accuracy of modern rangefinders I think there is less importance attached to how flat the trajectory of a bullet is.

For hunting calibres I believe that terminal performance is more important than the projectile’s ability to cheat the wind. I invest more time practising my wind calls and knowing my limits when it comes to wind.

Terminal ballistics

Let’s explore terminal ballistics. Terminal performance is how the bullet performs when it strikes its target, and this is a combination of the calibre, the projectile, and the make-up of the animal you are shooting and where you shoot it.

A bullet that is very good for ‘ringing steel’ on the range may not be the most effective hunting calibre. The same bullet will have a different effect on the same animal at the same range, depending on where you place the shot. Factors such as striking bone and the position of the animal will have an effect on the size of the wound channel and how that performs in terms of killing the animal.

The more ‘volatile’ projectiles can work well on deer in the hunting conditions found in the UK and Ireland. Credit: Jason Doyle

There are three main ways that a bullet effectively kills game: the first is what we often refer to as a ‘shot to the vitals’. This is considered best practice and the objective is to cause enough damage so as to stop the functioning of the heart or lungs. The more damage we can inflict on the heart or lungs, then the quicker they will fail to work.

The second is a spinal shot; the target here is quite small as it will only be effective if the spinal cord itself is damaged, and for that reason accuracy is a primary requirement, as is a trained dog in order to follow up since these shots often merely paralyse the deer. A projectile that expands well and has good penetration will be able to effectively dispatch the largest of stags.

Some will say that a small calibre can be used to effectively on deer if you are head or neck shooting – this is true to a point, but I have seen it go wrong as well, especially with neck shots. The head is often a larger target than the neck when wind is not an issue, and it is an effective means of dispatching an animal, but again it should be reserved for situations that demand it and facilitate good accuracy.

Always be aware that frontal headshots at close range can go wrong in a hurry, even with .30 cal bullets. What can happen quite easily is a shot that strikes the lower jaw, detonates and fails to penetrate the neck – for this reason it is always important to know how low your bullet will strike at ranges form 20 yards to 100 yards.

A bullet’s performance on the range and on game can differ significantly, and what is best for one may not be best for the other. Credit: Jason Doyle

What all of this tells us is that shot placement is paramount, but when things go wrong the larger calibres with a bullet matched to the animal will be more forgiving.

In an ideal world you want a bullet that transmits good energy, creates a large wound channel and a large exit wound while still being easy to shoot in hunting situations. In my experience, how easy a rifle is to shoot has as much to do with the rifle design and set up as it has to do with the calibre.

Sectional density

Sectional density, in layman’s terms, is a number that reflects the weight and diameter of a bullet. We have seen a rise in popularity in the 6.5 calibres recently, which seems to be driven by their mild recoil, high BCs and inherent accuracy.

From a hunting perspective there are some who hold the experienced opinion that these long, thin bullets perform like a spear – this is good for when they are in flight (external ballistics) but results in poor performance on animals (small hole in, small hole out).

Of course, suitable bullet construction will help performance, as will shot placement. In general terms, however, these 6.5 calibres lack the sectional density of the 7mm and .30 calibres, and thus they pack less punch.

There is of course always going to be a place for the smaller ‘big game’ calibres, and your hunting scenarios and recoil tolerance will dictate this to a large degree. .243s and 6.5s are lovely to shoot and very effective on deer, especially in woodland stalking scenarios. What I am looking for is that calibre that strikes the perfect balance between shootability and terminal performance, and for that reason I now favour calibres from .270 up.

Which one do I choose?

The .270 Win, in my opinion, is the starting point for mountain hunting. It maintains over 1,300ft/lb of energy out to nearly 400 yards with a 130gn bullet, and out to 450 yards with a 150gn bullet. At ranges beyond this it is likely that you will not get an exit wound on deer-sized game.

The .300 Win Mag and WSM also have their fans. What I have experienced is that the likes of the .300 Magnums have incredible knockdown power, the effect on the animal is very visually noticeable, and in turn there is more forgiveness for poorly placed shots (within reason).

I shot a .300 Win Mag for some time in a cumbersome rifle of 20lb. It was capable of phenomenal accuracy, but I found that it ‘took a lot of shooting’ – in other words, its performance was very dependent on how I set up for the shot. I also found that it was very prone to torque on the shot, in that it would twist and often cause you to lose sight of your strike.

The .30-06 has similar recoil to a .270 Win, but is noticeably more effective, even more than the data on paper might suggest. This, I believe, is down to sectional density.

I recently had an opportunity to test two Sako 85 hunting rifles, one in .270, the other in .30-06, both weighing under 10.5lb scoped and silenced and both fitted with Hausken moderators. The difference in recoil was not noticeable, but the effect on animals was.

On the other hand, if you were to compare a .300 Win Mag and a .30-06, on paper the Win Mag would come out on top, but in practical terms I would favour the Aught Six any day, predominately based on its shootability.

Recoil and ammo

If the circumstances allow, a muzzle brake can really allow you to tip the scale in favour of some of the larger calibres. I once had a .338 Lapua Magnum that was fitted with a very effective muzzle brake, weighed 20lbs and was an absolute dream to shoot.

From a hunting perspective it would be quite limited in the circumstances where you could use it, and hauling it around would get old fairly quickly. But personally speaking, it did demonstrate that it is possible to tame the largest of calibres.

The calibre debate for me is often limited to the theoretical due to ammunition availability. I need to be able to, firstly, have a range of ammunition available that will allow me to find a bullet that performs well in my rifle and is suitable for hunting; and secondly, I need to be able to get a sufficient quantity of that ammunition to facilitate practice and hunting.

I would really like to try the 7mm WSM since its theoretical performance is impressive. Unfortunately, the limited range of ammunition and its scarcity off the shelf means it’s a non-starter for me.

From my own perspective I am still looking for that calibre that will deliver maximum terminal performance, be smooth recoiling, and not exceed 11lb on the scales (including the scope and moderator). The search for the ultimate calibre continues – when I find it I’ll let you know.

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