I recently purchased a new bolt-action rifle chambered for the 6.5mm Creedmoor cartridge and some friends have been asking why I specifically selected that cartridge. So I will attempt to answer that.
I started by making a prioritized list of my requirements and wants for a deer hunting rifle. Here is what I came up with:
- Cartridge must be capable of taking medium game at up to 500 yards
- Must be a bolt-action rifle with detachable magazine
- Preference given to lighter rifles
- Preference given to lighter recoiling cartridges
- Would be nice to have a cartridge that is also usable for taking large game
With this list in mind, I used some internet wizardry to look for mild recoiling short action cartridges with a healthy variety of factory hunting loads available on the market. I narrowed down the list of cartridges to four options for a detailed comparison: .243 Winchester, 6.5mm Creedmoor, .308 Winchester, and 7mm-08 Remington.
In terms of velocity, all four cartridges perform well and retain sufficient velocities at 400 yards to ensure consistent bullet expansion. At 500 yards, the .308 Winchester and 7mm-08 Remington come in just under the 1800 feet per second threshold for expansion of common soft point hunting projectiles. However, this can be mitigated by selecting hunting loads that use a polymer tip to help initiate expansion. Given this data, I will award 1 point to the .243 Winchester and 6.5mm Creedmoor towards being the winner. The table below summarizes advertised velocity performance of Federal Premium Fusion hunting loads (which I’ve used for comparing cartridges):
Next I took a look at energy. I’ve read in many places about the 1000 foot-pounds rule of thumb for dispatching game ethically. While there is more to terminal ballistics than this “rule of thumb”, I am applying it to cartridge selection anyway. At 500 yards, the 6.5mm Creedmoor and the .308 Winchester are the two cartridges that advertise more than 1000 foot-pounds of energy. So they are awarded a point each and the 6.5 Creedmoor takes the lead with 2 points. The table below summarizes advertised energy performance of Federal Premium Fusion hunting loads:
Next up, a wind drift comparison. To be honest, I’m splitting hairs here. The difference between the best advertised performance of the 6.5mm Creedmoor and the worst advertised performance of the 7mm-08 Remington at 500 yards is 2.2″. The least drift was 22.1″ and the most drift was 24.3″ assuming a 10mph cross wind. This is another win for the 6.5 Creedmoor and therefore increasing its lead over the other options. And here is the wind drift table (smaller number are better):
Finally, a drop comparison. The difference in drop is more pronounced than wind drift was. Drop is a result of the time a bullet in flight is exposed to gravity. The less time in flight the less a bullet drops. And the clear winner in this category is the .243 Winchester. It’s the fastest bullet out of the muzzle and the fastest bullet out at 500 yards. The table below summarizes drop for these four cartridges:
If I managed to keep score correctly, our winner was the 6.5mm Creedmoor with 3 points, followed by .243 Winchester with 2 points, .308 Winchester with 1 point, and 7mm-08 Remington with 0. I suppose I could have also disqualified .308 Winchester and 7mm-08 Remington for falling below 1800 FPS at 500 yards and .243 Winchester for falling below the 1000 ft-lbs at 500 yards. But either way I look at it, the 6.5mm Creedmoor came out on top.
What about recoil? A recoil comparison required some additional internet wizardry with a sprinkling of spreadsheet fairy dust. Felt recoil to some extent is subjective, but one can calculate recoil impulse mathematically by considering the weight of the rifle, weight of the projectile, powder charge weight, and projectile muzzle velocity. Taking the most accurate load data from Nosler’s load data and plugging it into a spread sheet using a static rifle weight of 5.2 lbs results in 6.5 Creedmoor yielding the lowest recoil, followed by .243 Winchester, then 7mm-08 Remington, and finally .308 Winchester. Yet another win for 6.5 Creedmoor. The following table summarizes my magical numbers:
But what about penetration? My research indicates that projectiles with greater sectional density (mass of the bullet divided by the bullet diameter) yields the greatest penetration. This is measured in pounds per inch. I went back into Nosler’s load data and found the sectional density for each of the projectiles used in my recoil impulse calculation and found the following:
|Cartridge||Bullet Weight||Sectional Density|
Lo and behold, yet another win for the 6.5mm Creedmoor. Sure heavier weight bullets will have greater sectional densities, but they will also have greater recoil impulse. But even when looking at the sectional densities of the heaviest Nolser Ballistic Tip projectiles, the sectional densities of the .308 Winchester and the 7mm-08 Remington were less than the sectional density of the 140 grain 6.5mm Creedmoor.
On paper and in my opinion, the clear winner for my priorities in a deer hunting cartridge is the 6.5mm Creedmoor. Will my homework yield good results in the field? I don’t know, but I will find out during this next hunting season.