As I was given the task of testing a bolt action Carbine and a cutting-edge riflescope – a Remington 700 VTR chambered in .308 Win and a Zeiss Diavari 3-12x56 T * with Rapid Z5 reticle – I found myself in need for a round that could keep this relationship going. The ballistic tables on which the Zeiss Rapid Z5 project relies have taken inspiration from the standard trajectory of the 10.7g - 165 grains Blaser CDP .300 Winchester Magnum. The hunter is mostly interested in selecting the best magnification levels on the riflescope according to the ammo, specifically the falling rates of the ball with respect to standard ammo. In my case, since I have picked the .308 caliber Hornady InterLock SST Light Magnum 150 grain bullet, I set the appropriate magnification level of the riflescope to 12x. After zeroing the weapon at a distance of 100 meters, I fired three rounds at 200 m and detected the mean POI of the shot pattern only 3 cm higher than the mouche. So I took three more shots within a 200 m distance, this time using the 300 m reticle notch in order to verify the extent of the increase, which turned out to be 16 cm. This leaves us, with respect to the table provided by Zeiss, with a 7 cm difference. Why is that? Simple. The fast Hornady InterLock ball moves down 6 cm less than the reference ammunition. However, if we use a common spitzer ball of 150 grain (Federal Power Shok 150 grain, for example), this gap would cease to exist. In fact, according to the tables, the SST Hornady has an increase which is 2.2 inches (5.6 cm) greater than the Federal.
Since the hunting targets were basically deer, fallow deer and wild boars, I looked for an ammunition striking a good compromise between ballistic needs – which were quite demanding given the size of the game – and the technical constraints posed by the Zeiss Rapid Z5. After taking a look at the basic features of the various ammo, I finally picked the Hornady Light Magnum SST, with a 150 grain Interlock ball. With the help of this trio, I was able to get a 41x31 mm group at a 300 m range – quite a remarkable result if we consider that I was using a commercial loading.
As a matter of fact, I had already employed a SST Light Magnum with Interlock ball and with a 7x57mm Mauser caliber last season, when I was hunting deer. At that time I had been really impressed by their performance, so as to state that such an old caliber seemed to have been born again with the help of the new Hornady ammo. I was therefore thrilled with the idea of trying the .308 150 grain version for hunting larger wild animals, so as to make a more comprehensive assessment of this ammo. I have to admit that performance was equally high, considering that I was able to take down two wonderful fallow deer and two roe deer within very different distance ranges (one at 55 m and the other one at 187 m, one at 91 m and the other one at 223m).
The two most positive features of this ammo are accuracy and stability – that is the ability to balance penetration and energy transfer. In none of the four wild animals shot down was the ball still in the spoils. Considering that none of the animals moved further than 3m after the shot, we can say that this bullet has a potential to be used against stronger wild animals – i.e. red deer.
The SST bullet – acronym which stands for Secant Spire Tip – comes directly from the Interbond. The latter, a renowned bullet, already had a polymer tip, boat-tail profile and a welded core. The SST is basically an evolution of the Interbond since, in addition to having similar ballistic coefficient and sectional density, it features a thicker jacket and a beefed-up bar which allows for stronger penetration and greater weight retention.
This innovative bullet meets the specific needs of those hunters who are looking for a bullet to be precise and effectively deadly without destroying the meat and trophy.
It might be interesting to know that this bullet, in its 180 grains version with a .30 caliber, launched at 3080 fps has a penetration rate through ballistic gelatin of 10 inches (25.4 cm), with a 47 percentage of residual weight. At a lower speed – i.e. 2000 fps – however, penetration reaches 12.5 inches with 89% of residual weight. These figures are 10% higher with respect to the performance of similar bullets from other competitors.
The SST is a polymer-tipped bullet; this tip has a triple function. First, to improve the weapon feeding while keeping the structure of the bullet unchanged. Second, to improve the ballistic coefficient in order to obtain a tighter and faster trajectory. Third, to control its expansion within a larger speed range. Furthermore, the SST has a thick ring-shaped layer within the jacket, known as Interlock Ring, which ensures that the jacket and the lead core are properly sealed during the phases of expansion of the bullet upon its impact with the target.
For this reason, Hornady has put this type of bullets in its highest-quality commercial cartridges, that are the Light Magnum, the Custom and Superformance.
These cartridges have become extremely popular in the US and in all those countries where there is a strong demand for hunting rifles scoring a very good performance at medium and long distances.
Accordingly, this type of bullet is also enjoying widespread popularity in African countries, where long-distance shooting is quite popular (Namibia and South Africa), and in the Middle East for goat hunting across the hills. The SST is also used in the Alps and in certain regions of the Italian Appennini to hunt deer and wild roe. Within the .308 caliber, Winchester Hornady offers both 150 and 165 grain bullets. They are both available as plain bullets for reloading. This offers the hunter the opportunity to extend his operational range to larger wild animals such as the red deer or the large African antelopes.
Here are some of the ballistic details of this ammo
Hornady SST LM Interlock 150 grains (8593)
Ballistic coefficient: .415
Sectional density: .226
Muzzle speed: 885 m/s
Muzzle energy: 414 Kgm
Energy at 90 m: 353.6 Kgm
Energy at 180 m: 300.5 Kgm
Energy at 270 m: 253.8 Kgm
Energy at 360 m: 213 Kgm