Monday, April 26, 2010

Why are not today’s super magnums used in modern doubles?

Dear Cal:
Why are not today’s super magnums used in modern doubles (or re-chambered to older doubles)?
Gary Hopkins, PH, Zimbabwe

It is always good to take a question from my friend and PH!

Today’s fascination is with cartridges that hit harder and go faster so it may be a surprise to many that more are not seen in double rifles of modern manufacture or re-barreled or re-chambered in vintage rifles. However, there are five problems with this. First, the mentality of the super magnum desire is to reach out and shoot one’s elk, or sheep, or antelope at 700 yards. Anything beyond 150 yards is stretching it for the double rifle due the regulation complexities. No matter how optimistic the folding sight leaves say the range may be, double rifles are not long range rifles by any means.

Second, is the muzzle blast and how it affects shooters. The higher velocity of modern magnums gave rise to the muzzle brake or porting of some sort. Neither is conducive to accuracy in a double rifle. Besides being down-right ugly (author’s opinion) and as far from traditional as one can imagine, muzzle brakes would destroy regulated accuracy. Also (and third), they are death to the ears of those in close proximity. In fact, many PHs in Africa will not allow their hunters to shoot with a brake.

Number four, is the pressure in the modern magnums are too high for most doubles. Many cartridges have a pressure of 60,000 psi whereas some of the larger nitro cartridges are half that or less. Remember the British used the larger cartridges to achieve lower chamber pressure in the heat of Africa and India (cordite was very hear sensitive). The double rifle action is far weaker than a bolt rifle and high pressures caused difficulty in opening the action after discharge.

With the above, and last on the list, is extraction difficulties. High pressure makes extraction more difficult and ejectors can tear through the thin rim if the cartridges sticks in the chambers. And, today’s magnums are of a rimless design and rimmed cartridges work best in double rifles.

I guess I should add another. The forte’ of a double rifle is dangerous game hunting. Most high velocity magnums are for long range shooting and use light weight bullets. 500, 570, 750, and 900-grain bullets are for close up work and not for shooting across a canyon in the southwestern USA. A double is for quick, snap shots at critters that can hit back and, no matter what Roy and others say, I would rather have a 500-grain bullet at 2150 fps (or 900 grains at 1950!) rather than a 180 grain bullet at 3600 fps. ‘Nuff said!

Good shooting,

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