There is no doubt that calibre choice is a touchy subject. When you try to compare the varying performances between certain calibres and cartridges, people often have a favourite and that is that. There is nothing wrong with this and if it is not broken then why fix it? But simply because you have used the same cartridge and bullet for deer or foxes for years does not mean it is necessarily the best. Where deer are tricky to stalk or the shots are long, a flat-shooting calibre may be your tonic, but to me the extra noise, recoil and cost of ammunition is a disadvantage. With a lighter cartridge, loss in power can be counteracted by precise bullet placement and bullet performance. The vast majority of deer I shoot are at short range. Rarely does a shot stray more than 150 yards, in fact, 50 yards is more the norm and in these instances a normal cartridge such as a .243 or .308 can often be overkill. You can reduce the load if you reload, but ballistics dictate that a case designed for the
smaller powder charge is more efficient.
Savvy shooters have been using smaller yet highly efficient deer cartridges for years. Their size often belies them over the ranges indicated above and they present no disadvantage whatsoever. Moreover, the low muzzle report and recoil are beneficial both to the stalker and environment, and with a proper bullet of the right construction they can be just as lethal yet cause less damage to the meat.
Old and new
So which calibres and cartridges are we talking of here? To keep things simple I have chosen two commonplace examples and a couple of newcomers. These are the 6PPC and 6mm BR and the newer 6.5×47 Lapua and 6.5 Grendel. Each has a short and rather fat case design. This seems to give the kind of efficient powder burn that achieves good velocities and great consistency with minimal powder, which is, of course, the aim. The 6PPC and 6.5 Grendel use one of the best kept secrets in ballistics and that is the .220 Russian case, which is expanded at the neck to the required calibre and then fire-formed to the new cartridge dimensions.
The 6mm BR is nothing more than a stubby .308 case, but approximately half the size, and the 6.5×47 Lapua is a ¾-size .308 case necked-down to accommodate the slim 6.5mm projectiles.
With many of these calibres and cartridges, especially the 6PPC, barrels must be no shorter than 24in to achieve legal velocities for deer. If you shoot north of the Border you should keep in mind the 100-grain minimum bullet weight for larger species of deer. However, for the minimum input there is maximum output, which, from a stalkers point of view, is just fine.
The 6PPC is an absolute gem of a case that has dominated bench rest target shooting for decades. These days it has a fervent following among stalkers and fox shooters. As far as ballistics are concerned, it has the minimum capacity and some of the lighter bullets do not make the grade. However, fired from a suitable barrel with a rifling twist of 1 in 12 or less, to stabilise a 70-grain bullet or larger, the PPC is superb. Twenty-nine grains of Hodgdon H322 powder sends a 70-grain bullet out of a custom-built 26in barrel at 3,362fps and generates 1,756ft/lb of energy. It just meets the legal requirements but wins on its very light recoil, the ease with which you can moderate the rifle and the fact that you can actually spot your shots. That you suffer no flinching ensures far better shot placement than with a cartridge with heavier recoil.
Similarly, if you need to shoot 100-grain bullets then 28 grains of RL 15 will do the trick, producing 2,743fps and 1,754ft/lb. But you need to remember that, with this weight of bullet, unless the rifles chamber is throated to accept these long bullets, they will have to be seated much farther into the case than is practical and have a faster twist rate.
A much better bet in terms of a practical cartridge is the 6mm BR. The normal or standard .308-size head unlike the dedicated PPC suits far more rifles. Lapua makes cases that need no work prior to reloading and as such are an easier proposition. Again a small charge of only 29.5 grains of either Vit N133 or Hodgdon Benchmark propels a 70-grain projectile at more than 3,362fps from a 26in barrel, achieving 1,757ft/lb energy. The BR case is better suited to the heavy bullets as it is often throated to accommodate them, and a 100-grain Game King can be shot at 2,784fps and generate 1,807ft/lb of energy with a powder charge of 28.5 grains of RL 15. Similarly, the same powder with 32 grains dead will push an 80-grain bullet at more than 3,161fps to give 1,775ft/lb. These are all close to the legal limit for some deer species but in a real-life deerstalking scenario they are incredible performers.
With the 6mm bullets covered, lets turn to some efficient 6.5mm variants. Here, there have been significant inroads into cartridge efficiency, all led by the target fraternity but still just as useful to us stalkers. Only a change of bullet type is necessary. Though I love the .260 Remington a truly versatile 6.5mm cartridge there are two new 6.5s that have taken off a storm. First is the unusual 6.5 Grendel, which is nothing more than an improved 6PPC case necked-up to fit a 6.5mm bullet. At first glance it looks incapable of pushing a pea up a straw, so small are its dimensions, but this cartridge is just right. Though you can use lighter bullet weights, I will start with the 129-grain weights, primarily the Hornady SST loads, which have worked very well for me over the years. Again they are seated rather long, which is good as they feed well through a standard magazine with little modification. A 129-grain SST with a load of 28.5 grains of Hodgdon Varget generates 2,551fps velocity and 1,864ft/lb of energy from a 24in barrel. This is more than good enough and with a bullet as slim and with as high a ballistic coefficient as the 6.5mm it is very wind- bucking indeed and thus loses less energy at longer range.
If you go up to a 140-grain bullet, say the Hornady Interlock, which is a good solid deer-proven projectile, then the same load of 28.5 grains Varget generates 2,473fps and 1,902ft/lb, still in safe pressures. With that type of performance at sensible deer ranges, you can see why its odd to bother with anything that kicks more and uses more powder.
The final option is a little more conventional and may be the best. Why? Well Lapua makes the cases so they are naturally extremely good. It uses a small rifle primer to aid consistent powder burn for this powder charge weight.
As an intermediate round as regards length, it bridges the gap between .308-size derivatives such as the .260 Remington better than the smaller 6mm BR case, for example. On the new 6.5×47 Lapua, the 47 denotes the case length in mm (a .308 is 51mm, so you are between that and a BR cartridge of just over 39mm).
The proof is in the pudding and a Lapua 6.5mm x47 will send a 129-grain Hornady SST bullet out of a 24in barrel with 1 in 8 twist rifling at 2,796fps and 2,240ft/lb, with only a powder charge of 40 grains Hodgdon H380 superb! Switching to a heavier bullet with a 140-grain Interlock also from Hornady and a charge of 40 grains IMR 4831 SC, you get a very healthy 2,681fps velocity and 2,235ft/lb energy. This is legal for deer in any part of the UK and super-efficient with minimum fuss, noise and recoil. You name it, the 6.5×47 Lapua does it.
The question is, if you own a .243, .260 or .308 rifle, would you rebarrel your rifle for one of these new, more efficient cartridges? The answer is probably not, but if you only stalk in more populated areas or at short ranges then all these cartridges are worth consideration. It is true that you have to choose the bullet weight and velocity carefully to stay legal for some deer species or regions, but for smaller species and foxes these are highly efficient cartridges. You will also appreciate the lack of recoil, noise and better accuracy as far as your shootings concerned and smaller cartridges cause less damage to venison. The firearms industry must be cottoning on to a demand for these calibres because Hornady has just introduced a shorter, highly efficient 6.5mm cartridge called the Creedmoor. Thompson Center has done likewise, producing the venerable .30 calibre with the 30TC round.