(Continued from Part 4.)
More on the 6.5 Creedmoor
In its development, many aspects of the 6.5 Creedmoor were combined to produce a very accurate cartridge. The 6.5×55 barrel twist rate is 7.8:1 and the twist rate for most 6.5CM rifles during its introduction was 8:1. This is ideal for the heavier 140 to 160 grain 6.5mm projectiles that give both of these 6.5 cartridges very desirable ballistic properties and fine accuracy. The long bearing surface of heavy-for-caliber bullets impart stability inside the barrel and outside the barrel as yaw rates are lower and the bullet settles down and could become more accurate as it travels out to long distances. In other words, if the cartridge shot 1 MOA at 100 yards one would expect that it would continue to hold 1 MOA at 400 yards and result in a 4-inch-diameter group. However it does happen on occasion that the round could become sub-MOA out past 300 yards as the bullet’s yaw rate decreases. (The stability actually increases, in flight.)
The effects of the wind is the factor that will most likely blow the bullet around and open up the group on distant targets. In the case of both 6.5×55 and 6.5CM, the difference in how much the wind can blow the bullet off course is cut in half between 400 yards and 300 yards. In a situation where there is a 10 mph crosswind the 143-grain ELD-X bullet that had a muzzle velocity of 2,700 fps would be deflected 9.7 inches at 400 yards, but only 5.3 inches at 300 yards. One might be able to shoot MOA out to a distance, yet the wind will likely open up the group significantly. This is why I set my long-range hunting shooting limit at 300 yards.
Some 6.5 CM rifles are being offered with slower twist rates. I mention this to alert readers interested in purchasing a 6.5CM to beware that there are some 6.5CM rifles now offered with barrels with a 1:9 twist rate instead of the optimal twist rate of 1:8 for our long-range shooting requirement. The 1:9 twist rate would be acceptable and optimal for projectiles that use a shorter and lighter 120-125 grain bullets that have lower ballistic coefficients, and offset a lower ballistic coefficient with higher velocities within 500 yards that also produce a flatter-shooting cartridge while retaining exceptional accuracy for that lighter bullet weight. This is ideal for hunting smaller deer and varmints. The 120-grain 6.5 projectiles are not as accurate in barrels with 1:8 twist rates, producing at best only 1 MOA accuracy. This degrades over longer ranges. Therefore the 1:9 twist rate is being offered. So we must choose between the two twist rates currently offered based upon the sort of game that is most likely available to hunt.
I would avoid 6.5CM barrels with the slower twist rate. This slower twist rate would be acceptable or preferable for shorter barrel lengths that make a hunting rifle handier in the field, yet given the lackluster performance of 140 grain 6.5 projectiles on game heavier than 250 pounds beyond 200 yards, I would stick with the 1:8 twist rate and projectiles that are 140 grains and heavier as that is the best balance in terms of accuracy and maximum killing power. My advice, if you want a 6.5CM, is to be sure to get one with a 1:8 twist rate. Most of the inexpensive entry-level 6.5CM rifles are very accurate straight out of the box. But because these are marketed for hunters, they could have a 1:9 twist rate instead of the tried and true )and more preferable in my book) 1:8 twist rate that makes the 140-grain and heavier bullets as accurate as they are.
Other Long Range Rifle Cartridges
The 6.5 Creedmoor (CM) is an excellent long-range deer rifle. It is ideally suited for this role. I would however not attempt to take elk at beyond 200 yards with the 6.5CM, and I would use a premium bullet such as the 140-grain Nosler Partition if hunting elk with this rifle.
The .270 Winchester would also be a good choice, perhaps a better choice. In 1925, Winchester released their Model 54 bolt action rifle chambered in the new .270 Winchester cartridge. As it set the standard for long-range deer and antelope hunting almost 100 years ago, we might wish to dust off our .270 rifles. If the .270 Winchester you have shoots MOA and you can shoot it well given the increase in recoil, I would use Hornady’s commercial ammunition that uses the 145 grain ELD-X ammunition for long range deer and elk hunting.
Or, Federal’s version, using the same bullet.
Because this .277 145 ELD-X bullet is launched much faster at 2,890 fps versus the 143 grain ELD-X 6.5CM bullet at 2,700 fps, it bucks the wind just as well as the 6.5CM or 6.5×55. In addition, it delivers much more killing power on the target allowing shots on game up to elk in size. In retrospect, the old .270 is still one of the best. And it might be the best choice given its relatively low recoil that promotes good shot placement coupled with super flat trajectories. The next step up would be the 7mm Winchester Magnum, if you can avoid flinching. Yet I still consider the old Ought 6 (.30-06) as the most versatile cartridge out there. It can propel a 150 grain bullet upwards of 3,000 fps, and 180 grain bullets at 2,820 fps. If we could only have one gun, then this is it. And indeed, I would beware of the man with only one gun as he likely knows how to use it. As we’ll see later, the .270 Winchester is the most sensible long-range rifle for hunting deer and elk. If you have one then you are ‘good to go’ and need not look further.
I can recommend the entire Hornady ELD bullet line and Hornady’s line of cartridges that use their ELD-X bullets, and their Superformance lines of commercially available ammunition that use the SST bullet for long-range hunting as well. One will shoot better than the other in your rifle. If your budget and rifle prefers something else, I would test Federal’s hunting ammunition that also use Hornady’s ELD-X, or all of Federal’s ammunition. It is just as likely to shoot MOA in your MOA-capable rifle and may cost less. Use Ammoseek.com to shop for the lowest-cost ammunition and reloading components. If your rifle is in good condition most commercial ammunition should be accurate enough for hunting out to at least 200 yards.
Intro to Some Ballistic Charts
Tomorrow, in the sixth and final installment of this article will be a short list of common cartridges that can be used for comparative purposes. The JBM ballistics calculator was used to generate the numbers. This is a sample to give us an idea what each rifle is capable of and the method used to determine its maximum PBR (Point Blank Range) that is defined by a rise in the bullet’s trajectory of no more and 3 inches high and it’s fall to no lower than 3 inches low.
These samples are intended to be representative of most high-power cartridges that would be used for hunting at normal hunting ranges. In no particular order, these are commercially available cartridges that are considered to be flat shooting using typical bullet weights intended for light-bodied deer 250 pounds and under. At closer ranges, elk might be taken. It assumes the ammunition has the highest possible velocities that can be generated for the bullet weight when a full length 24-inch long barrel is used.
With the exception of .270 Winchester, Ammoseek.com lists all of these cartridges in its most frequently searched menu. The .270 Winchester was a very popular rifle among serious hunters for almost 100 years. There are lots of these rifles out there and its performance is certainly competitive if not superior. The charts examine two categories of ammunition for these popular and common caliber cartridges. These provide more than acceptable performance at the lowest cost. Category 2 looks at the latest and greatest performance ammunition for long-range hunting at a sensible price point. All but one example are of Hornady’s ELD (Extreme Low Drag) line of cartridges.
The odd man out in the charts is Hornady’s 160 grain .30-30 FTX that uses a flexible tip to greatly improve the performance, yet still safe to use in a tubular magazine. In a nutshell, category #1 is standard ammunition, and category #2 is high-performance ammunition. If you intend to “swing for the fences” out at 300 yards, then perhaps the high-performance stuff is worth the added expense. However, consider that if we can afford more ammo, then we can practice more often and be a better overall shot. Or, use the inexpensive ammo to train and shoot the good stuff sparingly. Most hunters will take game at under 100 yards. Only if your rifle is accurate enough, 2 MOA or less at 100 yards would I attempt to hunt with it at 300 yards. Hornady’s ELD line is well proven to be some of the most accurate ammunition out there and is used by the pros, and it is also affordable. It is worth a try.
The lightest weight bullet that is commonly found for sale in traditional hunting ammunition that is suitable for deer was used for each example to highlight the cartridge’s flattest possible trajectory. The .270 Winchester was the flattest by a wide margin, but the 6.5CM bucked the wind better by a wide margin therefore 6.5 is the winner. .30-06 and then .308 Winchester were the runner-ups.
Had we used modern ammunition, some of the best available from Hornady’s ELD line, the .270 Winchester would have easily beat out the 6.5CM example. Handloaders might be able to push their .270 Winchesters with 130 grain bullets with up to 62 grains of H4831sc to 3,150 fps. The 6.5CM example is using the latest in modern ammunition, yet now so can too the 99-year-old .270 Winchester to ring out its very best possible performance. Again, Ii you can afford the best, then you can forget the rest.
(To be concluded tomorrow, in Part 6.)