Hunting with a .243-6mm-.240

David Duffy

I could barely see two white specks on a rock platform way up in the hills. Grabbing my 8×30 binoculars, my suspicions were confirmed – feral goats. The Kimber 84M chambered in 6SLR would be fine on goats. By the time I reached the rock ledge, the pair had vanished. They had crossed into the neighbour’s property, so I came back down from the heights.

That afternoon, I decided to stake out a dam until dark. A deer came and had a drink, but I had plenty of venison in my freezer. A fox approached within 100 paces of the dam but did a sudden u-turn and ran. The 90-grain Speer destroyed him.

Popularity of the .243 Win in Australia far exceeds other commercial rounds in that bore diameter such as the 6mm Remington and .240 Weatherby – notwithstanding that they are also good hunting rounds. The .243 Win has mild recoil which makes it ideal for new shooters, but also for anyone who doesn’t like the recoil of the bigger rounds. It works well on medium-size game such as goats, pigs, wild dogs and also smaller game with its relatively flat trajectory. With accurate shots on larger game up to around the size of fallow, it can be adequate with the right projectile.

The design that Warren Page developed before Winchester commercialised the .243 Win had a 30-degree shoulder (rather than 20 degrees as on the .243 Win) and a longer neck and was made from 7.62 ordinance brass. Many years later, a similar lay-out using the .243 parent case has been developed for long-range competition use and is called the 6mm Super Long Range or 6SLR.

By changing the shoulder angle from 20 to 30 degrees which lengthens the neck, the long-for-calibre 6mm projectiles can be seated so the bearing surface is above the neck-shoulder junction (avoiding any thicker brass which may form at the base of the neck after repeated case firing) and still the loaded rounds fit in a normal short-action magazine. Other claimed benefits include less case stretching and reduced throat erosion resulting in longer barrel life.

There are now some really great long-for-calibre hunting projectiles such as the Sierra Gamechanger GameKing and the bonded Swift Scirocco 90-grain that have good ballistic coefficients and will work really well with a one in 9” twist barrel. Unlike some short, fat cases designed for competition use, the 6SLR feeds well from a magazine and the case capacity is sufficiently large to be able to shoot the 90-grain projectiles at a good velocity for hunting.

The 6SLR round is made simply by running a .243 case through a 6SLR sizing die. As some of the brass from the shoulder of the .243 case forms part of the neck on the 6SLR, the thinner Winchester brass not only gives greater case capacity but also reduces the problem of thicker brass on the inside of the lower neck which would require neck reaming. Bushing dies are available from Redding while Whidden does sizing and also bushing dies.

The 90-grain hunting projectiles are a good compromise if you only want to shoot one bullet weight. They shoot flat enough with minimal wind drift for varmints and work fine on medium game including small deer. I have found the 90-grain Scirocco to have excellent terminal performance holding together and mushrooming while maintaining around 78 per cent of its weight on game that I have shot. My 6SLR groups best with either 43 grains of AR2209 or 47.5 grains of AR2213sc at around 3120fps when using 90-grain projectiles. In my 6SLR I have been using the relatively inexpensive Speer Hot-Cors and I have just started to use 90-grain Sierra Gamechanger GameKings which are very long at 1.16” but with an excellent Ballistic Coefficient (BC) of .490 for their weight. These are seated 10 thou’ from the lands at 2.77” in my rifle. There’s quite a variety of other good hunting projectiles in .243 diameter.

Although I am a big fan of the shoulder shot with most calibres, on bigger game that has heavy bone structure such as an average size stag or a huge pig, the .243 diameter cup and core bullets may not always sufficiently penetrate past the bone to destroy the vitals and even with the premium bonded projectiles, the heavy bone can cause the projectile to alter the direction of the wound channel.

If the animal is quartering away, a behind the shoulder shot into the lungs is sometimes a better option than a broadside shoulder shot through thick bone. If regularly shooting deer such as fallow stags or bigger, well-constructed projectiles around 100 grains are recommended. Unfortunately, many bonded 100-grain hunting projectiles don’t have the high BCs as do some of the 90-grain projectiles, plus they aren’t travelling as fast, so their trajectory, wind-drift and energy retention suffers for those long shots past 270m. However, most shots are well within 270m and having a high BC is not important on the closer shots.

The mild recoil of the .243 and 6SLR rounds allow you to have a lightweight rifle that you can carry easily. My 6SLR Kimber SuperAmerica has a 23” one in 9 twist barrel and weighs a very light 3.18kg inclusive of Swarovski 3-10 scope. I’ve replaced the synthetic magazine follower with a custom-made stainless steel follower so there are no plastic parts on the rifle.

The 6mm Remington has more body taper than what I prefer. The .240 Page Souper Pooper increases the shoulder width and angle from 26 to 28 degrees and keeps the long neck so body taper is reduced and there is less case stretching and increased case capacity. The .240 PSP feeds well from the five-round magazine. With the standard .240 PSP reamer, the Scirocco projectiles are seated way out at 3.04” for maximum performance and this necessitates the use of an intermediate length action such as the Winchester Model 70 ‘short’ action which is perfect or a long action.

My accuracy load for the .240 PSP is 53 grains of AR2213sc with the 90-grain Scirocco at 3350fps out of a 24¼” barrel. The belted .240 Weatherby requires a long action, but gives about 50fps more with the same barrel length using two more grains of powder. I sight my .240 PSP 2” high at 90 and 180m and it’s down 2.3” at 270m and 6.3” at 320m. On a hunt for chamois or small trophy deer such as hog deer, Coues whitetail, roe deer, black-tailed deer, or wild dogs, coyotes and wolves where shots could easily stretch past 200m, the relatively flat trajectory of the .240 PSP and 90-grain Sciroccos is perfect. The moderate recoil facilitates good shot placement. If just using the .240 PSP on long shots at wild dogs, there is no need for expensive bonded projectiles, the Sierra Gamechangers would be ideal.

The high capacity 6mm’s do have a lot of muzzle blast/noise and there is no way that I would want less than a 24” barrel. However, using a 26” barrel makes the length too long and handiness would suffer. For general purpose hunting, I prefer to use a smaller case for longer barrel life and less expensive cup and core projectiles. This is where the 6SLR or .243 Win using the 90-grain Speer Hot-Cors projectiles are ideal. However, for its intended purpose, the .240 PSP with the 90-grain Scirocco projectiles in a Winchester Model 70 short action is hard to beat.

The case capacity of the .240 PSP, like the .240 Weatherby, is large enough to push well-constructed 100-grain projectiles fast enough to use it for bigger game. Warren Page went to New Zealand in 1956 and shot 14 red deer stags with his .240 PSP using 105-grain Speers. I prefer a bigger calibre for big game. I use RWS 7×57 brass to make the .240 PSP cases but Norma makes good quality 7×57 brass as well, or you can use 6mm Remington brass.

The next morning I continued to look for some goats in the hills as I really enjoy slow-cooked goat curry and I was out of goat meat. At the same time I was keeping my eye out for a billy with nice long horns but I wasn’t raising my hopes up too high. I was climbing up one of the hills to get to some open flats on top where sometimes the goats are and I saw one in the bushes 50 paces away. I raised the Kimber and aimed just behind the shoulder. The 6SLR did its job. Well now I had plenty of chevon. I would be trying for some pigs the next day.

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