Compared: The .25-06 Remington and .260 Remington
By Chuck Hawks
The .25-06 Remington and .260 Remington are both based on popular cases necked down to take smaller diameter bullets. The .25-06 is simply the .30-06 case necked-down to accept .257" diameter bullets. The .260 is based on the .308 Winchester case necked down to accept standard .264" (6.5mm) bullets. (Why Remington misnamed it the ".260" instead of the "6.5mm Remington" or ".264 Remington" is anybody's guess.)
Interestingly, the .308 was developed to replace the .30-06 in U.S. military service. Although the .308 case has something like 22% less powder capacity than the .30-06 case, in its military version, it produces the same muzzle velocity (MV) with a 150 grain bullet as the .30-06, but is designed for use in short action rifles. Both the .25-06 and .260 are covered in detail on the Rifle Cartridge page.
Although either cartridge can be loaded with light for caliber bullets and used for long range varminting, both are primarily medium game (CXP2) cartridges. The .25-06 is considered a long range deer and antelope cartridge with 100-120 grain bullets, but it is not generally recommended for hunting CXP3 game, such as elk. The .260 is more of an all-around cartridge, useful as a long range CXP2 game cartridge with 120-129 grain bullets and a moderate range CXP3 cartridge with appropriate 140-160 grain bullets. The greater versatility of the .260 is one of the main differences between the two cartridges.
Another notable difference is in the availability of rifles and factory loaded ammunition. Most U.S. rifle makers' chamber for the .25-06 and all four of the major American ammunition companies (Remington, Winchester, Federal and Hornady) load .25-06 cartridges. Only Remington and Federal offer .260 factory loads and fewer rifle manufacturers chamber for the .260. This situation is slowly improving, as word is getting around (partly spread by Guns and Shooting Online readers) about this excellent hunting cartridge and its popularity is on the rise.
Both cartridges are easily reloaded and there are many suitable bullets and powders available to reloaders. However, for the purposes of this comparison we are going to stick with factory loads. The SAAMI specified maximum average pressure (MAP) for the .25-06 is 53,000 cup and the MAP for the .260 is 52,000 cup.
Remington's name is on both cartridges and they offer three .25-06 factory loads using 100, 115 and 120 grain bullets. Federal offers four .25-06 factory loads using 100, 115 and 117 grain bullets. The popular 120 grain bullet used in Remington's factory load for the .25-06 is a Core-Lokt PSP (BC .362) at a muzzle velocity (MV) of 2990 fps. This is one of the the loads we shall use to represent the .25-06 in this article. The other is from Federal, their Premium Vital-Shok load with a 115 grain Nosler Partition spitzer bullet (BC .389) at a MV of 3030 fps. This will let the .25-06 take good advantage of its larger case capacity and potential higher velocity.
Federal offers three .260 factory loads and Remington offers four. In the Remington line, one .260 load comes with a 120 grain bullet and three with 140 grain bullets. One of the 140 grain offerings is a Core-Lokt PSP (BC .435) at a MV of 2750 fps, a similar design to their 120 grain .25-06 bullet. Remington's 120 grain .260 offering is an AccuTip Boat-Tail bullet (BC .480) at a MV of 2890 fps. These are the two factory loads we will use to represent the .260.
We will compare these .25-06 and .260 factory loads in velocity, kinetic energy, trajectory, sectional density (SD), cross-sectional area, killing power and recoil. Let's get started.
Velocity is the most important component of energy. It also decreases bullet flight time and hence flattens trajectory. Some hunters feel that high velocity per se contributes to killing power, but that is difficult to prove scientifically. Here are the velocities from the muzzle to 400 yards in feet per second for our selected loads.
I find these velocity figures interesting. Not unexpectedly, the 115 grain Partition, the lightest bullet in our comparison fired from the biggest case, is the speed king. It starts out 140 fps faster than the 120 grain .260 bullet, but at 300 yards the two bullets are traveling at virtually the same velocity. At 400 yards, the 120 grain .260 bullet is actually 43 fps faster than the 115 grain .25-06.
The 120 grain .25-06 bullet starts out 100 fps faster than the 120 grain .260 bullet. However, because of the AccuTip Boat Tail's higher ballistic coefficient, at 200 yards the .260 is actually traveling slightly faster than the .25-06 and beyond that distance the .260 increasingly pulls ahead. At 400 yards, the .260/120 is traveling 131 fps faster than the .25-06/120.
The .25-06's 120 grain Core-Lokt PSP starts out 240 fps faster than the .260's 140 grain Core-Lokt PSP, but at 400 yards it is only 53 fps faster. The .25-06's higher initial velocity confers less advantage than I would have anticipated.
Kinetic energy is the measure of a bullet's ability to do work. The "work" in this case is expanding and penetrating deep into a game animal to destroy the maximum amount of tissue and kill quickly.
Energy is an important factor in cartridge performance and killing power. Kinetic energy is a good indicator of the power of similar rifle cartridges. Here are the energy figures in foot pounds for our comparison loads from the muzzle (ME) to 400 yards.
Since about 800 ft. lbs. on target with a suitable bullet is a reasonable standard for humanely harvesting CXP2 game, it is clear that both the .260 Rem. and .25-06 are capable long range, medium game cartridges. Energy on the order of 1200 ft. lbs. at impact is about the minimum considered acceptable for hunting CXP3 game, along with a bullet capable of deep penetration, which is where the .260/140 has an advantage over the other three loads.
The .260 Remington and .25-06 are relatively flat shooting cartridges. The flatter a bullet shoots the less the shooter needs to compensate for bullet drop and the better his or her shot placement is liable to be. The following trajectories (in inches) are computed for the maximum point blank range of each cartridge/load (+/- 3") and assume an optical sight mounted 1.5" over bore and standard atmospheric conditions. Bullet rise and fall in relation to the line of sight are given from 100 to 400 yards.
The .25-06/115 NP has a MPBR of 293 yards when zeroed at 249 yards. The .25-06/120 C-L has a MPBR of 287 yards when zeroed at 244 yards. The .260/120 ATBT also has a MPBR of 287 yards when zeroed at 243 yards. The .260/140 C-L has a MPBR of 271 yards when zeroed at 230 yards and is inferior to the long range trajectory of the 115 and 120 grain loads due to its lower MV. However, within 200 yards, where the vast majority of big game is killed, there is no significant difference in the trajectory of any of these loads.
There is virtually no difference between the trajectories of the two 120 grain loads. This is because of the superior BC of the .260/120 grain AccuTip Boat-Tail bullet. Given 120 grain bullets of similar shape, say Speer flat base spitzer bullets, the BC of the .257" bullet would be slightly superior to the .264" bullet and the .25-06's higher MV would give it a somewhat flatter trajectory.
The fast .25-06/115 NP has only a 6 yard advantage in MPBR over the .260/120 ATBT load. At 400 yards, its drop is only one inch less than the .260/120 bullet. That is enough to give it a paper victory in this comparison, but little practical advantage in the field.
Sectional density is defined as the ratio of a bullet's weight in pounds to the square of its diameter in inches. SD is important because the greater the SD, other factors being equal, the deeper a bullet's penetration. Penetration is an important factor in the length of the wound channel and the amount of tissue disrupted. Obviously, to kill quickly a bullet must have sufficient penetration to reach and disrupt the animal's vital organs. Here are the SD numbers for our .257" and .264" bullets.
The .257/115 grain and .264/120 grain bullets are very similar in SD and both are well above the .225 SD considered excellent for CXP2 game. The heavier .264/140 grain bullet outclasses the .257/120 grain bullet in this important specification. It is the excellent SD of the 6.5mm 140 grain bullet that gives the .260 at least marginal CXP3 game capability.
Greater cross-sectional area means that, other factors (such as the percentage of bullet expansion) being equal, the fatter bullet should create the wider wound cavity, damaging more tissue and hastening the animal's collapse. Here are the cross-sectional areas of our two bullets in square inches.
It is obvious that a .264" diameter bullet has a greater cross-sectional area than a .257" diameter bullet, although the difference is not pronounced.
There are various ways to estimate killing power, all of which are approximations and none of which are entirely accurate. Bullet placement is the most important factor in a cartridge's effectiveness on game and it is a function of the shooter's skill and judgment, not the cartridge itself. The construction and performance of the bullet is also very important. The four bullets used in our comparison loads are proven performers in the field.
An attempt to include at least some of the factors relevant to killing power (primarily impact velocity and bullet weight) is the Optimum Game Weight (OGW) formula developed by Edward A. Matunas and published in the Lyman 47th Reloading Manual. Matunas assumed that bullet design and placement are adequate for the task at hand. The numbers below indicate the size of animal (live weight in pounds) for which each load is presumably optimum at ranges from 100 to 400 yards. (For more on OGW, see the "Expanded Optimum Game Weight Table" on the Tables, Charts, and Lists Page.)
The .25-06 has a modest OGW advantage from the muzzle to nearly 200 yards compared to the .260/120. At 200 yards and beyond, the superior BC of the ATBT bullet comes increasingly into play and the .260/120 edges ahead of both .25-06 loads. Not unexpectedly, the 140 grain .260 bullet scores highest in OGW across the board and it is the best choice for hunting larger animals.
Recoil is always an important consideration, as anyone can shoot better with a cartridge that kicks less. Remember that bullet placement is the most important factor in killing power. Presumably, one of the reasons for choosing either of these cartridges over, say, an equally flat shooting 7mm or .30 caliber cartridge is to minimize recoil. Here are the approximate recoil energy (in ft. lbs.) and recoil velocity (in fps) figures for our comparison loads, measured in eight pound hunting rifles.
As expected, due to its smaller powder capacity and lower MV with the same weight bullet, the .260/120 kicks less than the .25-06/120. It is, in fact, the lowest recoil load in this comparison. Perhaps a bit surprisingly, the fast .25-06/115 load kicks the most of our four comparison loads, despite its lighter weight bullet. Upping the .260's bullet weight to 140 grains puts it in the same recoil class as the .25-06.
The .25-06 has the advantage in initial velocity over the .260 and its 115 grain bullet shoots a bit flatter. It also has an advantage in the availability of factory built rifles and ammunition.
The .260 Remington wins this comparison in cross-sectional area and the .260/120 has the least recoil of our four comparison loads. The .260/140 grain load wins this comparison in the sectional density, energy and killing power categories and is essentially tied with the .25-06/120 in recoil.
Copyright 2012 by Chuck Hawks. All rights reserved.