(Continued from Part 4.)
Temperature Stable Powders
I will use temperature stable powder in these rifles so that during summer time temperatures, my previously safe-to-shoot cartridges is not adversely affected by an increase ambient air temperature or while chambered in a hot rifle barrel. H4895, H4831, H4350, and Varget are my top choices.
I engineer a wide margin of safety for powders that are not temperature stable and settle on a lesser weight charge. Accuracy can often be found at lower pressures when using lighter projectiles and at higher pressures if using heavier projectiles. Good accuracy for lighter projectiles is often found at top pressures and that is to be avoided in antique actions. Flat-based bullet will be more accurate than boat tail bullets therefore we can better avoid higher pressures when chasing accuracy.
If seeking top accuracy at lower pressures, it is better to use a heavy-for-caliber projectile that is also flat-based bullet. And because it is better to use a heavier projectile at lower velocities when hunting I will accept a hunting load that is not at top velocities. The recoil will be lower and the stress on the action lower.
If limited to hunting at “woods” ranges where we are likely to hit game typically at less than 100 yards, 3 MOA is good enough and the starting charge is likely good enough. To save time on load development and to be gentle on the action, I would use a starting charge with flat-based bullet that is soft and heavy for caliber. This would likely be plenty good enough for hunting inside where most game is taken, or 100 yards.
Ideally, develop your loads in the summertime and allow the cartridge to attain ambient or higher temperatures as part of the load development. When attempting to push the cartridge to near its maximum working pressure. Using temperature stable powders removes the necessity for this step.
The Ideal .308 Projectile for Antique Rifle Loads
I would prefer hunting with 180-grain or heavier round nose projectile in the woods, a projectile that is resistant to deflection if brush or tree twigs get in the way. Round-nosed bullets are typically designed for low velocities and are soft and expand quickly and complete with the minimum resistance from a deer-sized game and yet retain enough mass to penetrate out the other side that allows air to enter into two holes instead of only one. This causes the lungs to quickly collapse. High velocity cartridges rely upon hydro-static shock to liquefy the lungs and internal organs and the nervous system. Low velocity cartridges should rely on soft and heavy-for-caliber projectiles to quickly down the animal and the heavier and soft 180 grain or heavier deforms quickly and expands upwards of .75″ wide and will more likely produce an exit wound that causes more bleeding and ensures that the lungs collapse. The 150-grain round nose work well on deer within 75 yards at .30-30 velocities, but not as well on heavier game such as black bear or elk. For them, it is better to use the 170-grain bullet.
While .30-06 is minimum in my book, in an emergency, for Grizzly, my .300 Savage rifle can launch a 200 grain Nosler Partition at 2,150fps, or a 180 grain Nosler Partition at 2,350fps that might be enough bullet at ranges inside of 100 yards to stop a charging Grizzly. It would certainly be better than nothing and likely good enough to slow him down. And perhaps good enough break a shoulder and immobilize the beast. An impact at 50 yards, the MV would impart more energy and cause a significant increase in bullet deformation. Nosler Partitions are well known to provide wide expansion and deep penetration at lower impact velocities. They are the gold standard for hunting bullets. I have them for protection against Grizzly and other special occasions.
If you can afford these bullets, they are the outstanding choice, the best bullet for the lower muzzle velocities of antique rifles, or for that matter any rifle. There is no better bullet choice. But as I mnetioned, these are expensive and best reserved for large and tough big game. Big and slow is the way to go for dangerous game or large game animals such as elk and moose that we also find in our local forests. Each cartridge I’ve loaded with 200-grain Nosler Partitions is reserved for this kind of hunt. One expensive bullet is worth it if it gets the game. Elk are tough to put down and moose are much larger animals.
200 grain NPs (Nosler Partition) can be stabilized by the twist rates found in .308 Winchester and .300 Savage rifle barrels that are either 1:10. 1:11 or 1:12 and at the lower muzzle velocities of antique rifles. 2,150 fps is the slowest velocity I would accept, and if the barrel is less than 22 inches long, then the 180 grain NP is a better choice. Lower impact velocities will allow bullets that use a softer lead alloy would be less deformed and better penetrate deeply a toughly constructed big-boned beast. Shot placement, then penetration, and then bullet deformation are the important factors in this order of descending importance.
Other .30 Caliber Bullets For Antique Rifles
The .300 Savage that is within the performance range of most antique rifles chambered in a .308 bore diameter cartridge is in the sweet spot where you’ve got a tad more gun that can confidently take elk at woods ranges if you are so fortunate to run into one, and it will do so without the unnecessary recoil. For the woods a 180-grain RN inside of 150 yards and in the brush, but in the open, the Speer 180 SPBT (B.C .540) for as far out as you can hit well given the trajectory, and that might be 200 yards.
For flatter trajectories for hunting deer, the best bullet for .300 Savage performance level is the Hornady 150 grain SST, bullet number #30303, and second is the Hornady 160 grain FTX. Speer 180 grain BTSP is the best all around, and Hornady’s 178 grain ELD-X is a good alternative to the Speer 180 grain BTSP for black bear and elk. Both have extreme high ballistic coefficients approaching .540. All the aforementioned bullets are constructed to work well at impact velocities between 1,600 and 2,600fps. These bullets are excellent choices for the antique rifle shooting lower velocity projectiles. These are the most appropriate and versatile projectiles given limited velocities lower than .308 Winchester that I am aware of unless you can afford to shoot Nosler Partitions that have much lower ballistic coefficients — and cost 4 to 7 times more.
Nosler Partitions are ideal for antique rifles. You cannot go wrong with a Nosler Partition in any rifle if it will shoot it accurately within normal and realistic hunting ranges that seldom exceed 300 yards. But we are talking about a premium projectile that costs $1.10 to $2.00 just for the bullet. The Speer 180-grain BTSP is the overall best choice in all regards for “woods” ranges. Lighter Speer bullets will provide flatter trajectories and might be preferable if deer and antelope are on the menu.
Why pay more? Ammoseek.com informs me that I can get an all-around bullet like the 165-grain Speer BTSP bullets for as low as .26 cents apiece. That beats Hornady’s 160-grain FTX and Hornady’s 150 SST #30303 at .33 cents if the muzzle velocity exceeds 2,400fps. If the MV would be lower than 2,400fps, then the previous examples are a better choice. We should match the bullet to the capabilities of the rifle and shooter.
When buying a box of 1,000 bullets, the increase in the expenditure is noticeable, and the Speer 165 BTSP is soft enough for .300 Savage levels and is a better overall performer in terms of excellent accuracy, a good balance of penetration and expansion along with a flatter trajectory, and has the ability to buck the wind better when compared to the other choices. Not bad for only .26 cents per shot.
If the selection of bullets that can be purchased or is in the inventory of the reloader is limited, manuals such as Hornady’s 10th Edition catalogs their bullets for all cartridges and specifies the range of velocities that their projectiles were designed expand reliably in game within a range of muzzle velocities. The data is all in muzzle velocities rather than impact velocities.
Antique Rifles Chambered in Other .30 Caliber Cartridges
It is edifying to note that the original cartridge for the 1891 Argentine Mauser cartridge (7.65x53mm) has a large case capacity. It is 2 mm longer than the .308 Winchester case (7.62×51). This gave the 1891 Argentine rifle the ability to set the performance standards achieved by the modern U.S. .308 service rifles and light machineguns after the M1 Garand onward. A larger case capacity will hold the same charge that when ignited can produce the same velocities as a modern cartridge, yet at lower pressures.
Longer Barrels Produce Higher Velocities
The long 28-inch to 31-inch barrels (such as the 7.5x55mm Swiss) were necessary to achieve these velocities. A notable exception is the reduced brass case capacity of U.S. military ammunition — in particular 7.62x51mm NATO that is much more heavily constructed to be used in semi-automatic weapons, and therefore its case capacity is reduced, or less than commercial .308 Winchester brass. Therefore when using U.S. military brass, reduce the charge by 1 grain for all charges listed in a manual. To achieve higher velocities at lower pressures, I prefer commercial brass.
The very long barrels were needed to harness every bit of pressure in the barrel to impart a higher velocity to the projectile. The modern 7.62 x 51 NATO case head is the same diameter and its overall trimmed case length is only 2mm shorter. The projectile is only slightly smaller in diameter, .308 instead of the .311 diameter of the 7.65×53 Belgium or Argentine Mauser ammunition. The extra case length and capacity allow additional grains of powder to accelerate similar size and weight projectiles to comparable velocities that set the standard for 7.62 NATO ammunition that is produced today.
This class of full-power battle rifle cartridges that use .308 to .312 diameter projectiles stems from the performance standards set by 7.65x53mm. This includes 7.62x54R and 7.62×51 NATO and others that are time-tested battle cartridges that all perform within approximately the same performance level adopted by most militaries, early on.
For example here is the performance that can be expected from 7.62×51 NATO M80 ball that uses a 150 grain FMJ projectile using IMR4895 and the load data online at Hodgon’s Reloading Center. The data was obtained from the “.308 Service Rifle” section of Hodgdon’s Reloading Center. The stated velocity was produced from a 24-inch barrel using the maximum pressure loading recommended using IMR 4985 gun powder that was the standard powder for semi-automatic U.S. military rifles in 7.62 NATO M80 ammunition: IMR 4895, 150 grain FMJBT bullet , 45.3 grains produced 2,795fps at a the maximum pressure of 51,100psi.
Now let’s compare this load with the reloading data provided again by Hodgdon for 7.65x53mm Mauser that would be produced out of a 28.5-inch barrel. There is no SAAMI specifications for this cartridge. This load was hand-picked for the top velocity that produces around 48,800 psi (approximately 44,500 CUP), the average pressure limit for the maximum pressures Hodgdon recommends: Accurate 2495, 47.5 grains, velocity is 2,768fps, and the pressure is 48,800psi. It would be preferable to meet these performance standards if the rifle should be used in a counter-sniper role. Barrels that are 28.5 inches in length would make this possible if the maximum pressure that the action can handle is at least 49,000psi (44,500CUP) and it is a .30 caliber rifle.
(To be concluded tomorrow, in Part 6.)