Recoil

If the case sizes of .308 7mm08 and.260 are the same, why should there be less recoil from the .260 if all cases are filled?

All three calibres mentioned, .308 Win, 7mm-08 Rem and .260 Rem are indeed all based on the use of the basic 308 Win case, but the last two necked down to accept smaller diameter bullets. This allows a different choice of bullets styles which includes some of the most efficient designs with high ballistic coefficients for low drag, hence high retained velocity and energy, to be selected. Target shooters will employ these properties for reduced drop (flatter shooting trajectory) and lower wind drift at distance and hunters likewise plus the higher retained energy allowing similar retained energy at distance with lighter weight bullets.

Recoil produced in any firearm is largely the result of the weight of projectile and the velocity it leaves the muzzle at. Powder weight is a factor too, as it is part of the 'ejecta'  so has a mass that must be included in any calculations. Each calibre mentioned will be capable of holding a similar maximum charge volume, but the weight may not be the same as different weight of bullet, or the same weight in a different diameter, may require different powder selection, which will affect final charge weight. However, if a bullet of the same weight were loaded into each calibre, with a powder charge that achieved the same muzzle velocity then the recoil energy produced would be very similar for each with any variation being largely down to the different powder weight that might be needed to achieve these comparable ballistics. If fired from a gun of the same weight the recoil force on the shooter's shoulder will be equal.

Cartridges that use smaller diameter bullets, like those for the .260 Remington (nominally 6.5 mm diameter) have a reputation for light recoil because they are generally used with lighter bullets, perhaps around 120 grains and maybe less, compared with the .308 Win being typically 155 grains and more, often nearer 190 grains for long range use.It is these differences, not case dimensions/capacity that largely accounts for the lower recoil energy which must always conform to Newton's Third law of motion: to every action, there is an equal and opposite reaction.

As an example of the differences described, here are some examples of recoil energy as calculated by the Sierra Infinity Ballistic software for three max velocity loads taken from the Nosler manual. The weight of the gun is 10lbs in each case.

.243WCF 100gn / 3144 fps / 44.5gn powder = 9.9 ft/lb
.260REM 140gn / 2,830 fps / 45.5gn powder = 12.3 ft/lb
.308WIN  168gn / 2,820 fps / 46.0gn powder = 15.6 ft/lb

 We hope this helps answer your query.

 R.A. Target Sports

---

Related Articles