(Continued from Part 3.)
In my opinion, regardless if the chambering is .300 Savage, or .308 Winchester, or .30-06, using a temperature-stable powder at charge that delivers a muzzle velocity of 2,150 fps to propel a .308 150 grain round nosed bullet designed for the .30-30 is the safest practical load I could put together and recommend if the reloader is primarily interested in safety.
As an example in the extreme to illustrate that a larger case capacity is more desirable in antique actions. If it were chambered in .30-06, 35 grains of IMR3031 behind a 150-grain round nosed bullet will achieve and not exceed .30-30 pressures (38,000CUP) and performance levels suitable for hunting deer. I would prefer to have an 1891 Argentine Mauser chambered in .30-06, yet that is a topic for another time as it could exceed the performance of even modern .308 Winchester if the Mauser wore its original long 28.5-inch barrel. Yet those rifles would be hard to find, therefore I am happy to also own an 1891 Argentine Mauser in .308 Winchester that is closer to the original 7.65x53mm case and ammunition.
Relative to the smaller case capacity of .300 Savage, the additional case volume in both the .308 Winchester cartridge and the 7.65x53mm cartridge means more powder can be used to attain higher velocities at the maximum pressures for each type of action. A .308 Winchester or 7.65x53mm barrel operated at the same pressure that are under the maximum limit for 1891 Mausers that should be less than 49,000psi, can produce higher velocities than the same action rebarrelled in .300 Savage that has less case capacity. The import is that we can operate .308 Win and 7.65 mm Argentine cartridge at lower and much safer pressures and obtain an adequate amount of velocity and therefore use a wider selection of projectiles and heavier projectiles and impart greater killing power on game if a soft projectile is used. This is about safely getting the most performance from an antique, lower-pressure action.
Other measures can also be considered. The type of powder and a slower burning the powder used the latter and a diminished pressure spike would occur and lessen the stress upon the action. Some faster burning powders can get ‘spikey’ or exhibit non-linear or unpredictable pressure spikes when near the maximum recommended charge especially when the cartridge is heated up in a hot chamber or exposed to high summertime temperatures in a situation where a box of cartridges is exposed to the hot sun while stored on the dash of a vehicle. I’ll use a modern temperature-stable powders as a hedge against this possibility such as the H series of powders offered by Hodgdon. Conversely, temperature-stable powders will not be as affected by colder temperatures and there would be minimum change in the point of impact at longer ranges. This means the rifle does not have as great of need to be sighted in to compensate for seasonal changes. If I can at all help it, when charges are near the maximum or if loaded for precision rifles, I will use temperature-stable powders.
.300 Savage Performance in Antique Sporterized Rifles
Most rifles chambered in .300 Savage, with perhaps the exception of the Remington Model 81 and Savage 99 lever actions can likely can tolerate 51,000 psi as a working pressure. The Remington 722 and other American-made bolt actions certainly could handle much more, yet most small ring Mausers actions used in sporter rifles chambered in 300 Savage should not exceed 51,000 psi (46,000 CUP). After WW2 it became a widespread practice to rebarrel small ring Mausers in .300 Savage as this commercial ammunition made in the U.S. was easier to obtain, and because it was loaded to pressures these actions could handle (47,000psi/44,000CUP). At the time, it was good marriage.
.300 Savage ammunition is now expensive and difficult to find other than Hornady’s Superformance loading that is currently plentiful on the market. IHMO, Hornady’s Superformance Ammunition is too hot for 1891 Mauser actions. Once that supply has dried up, I suspect the price of .300 Savage will be closer to $2 per round and higher. Today it is easier to find 7.65x53mm at just over $1 per round from PPU. For the reloader .308 Winchester that is similar in case capacity and allows the use of a vast array of .308 bullets, is the better choice.
For advanced reloaders who would experiment with wildcat methods, I will say no more than it is possible to gain a tad more performance from some bolt actions chambered in .300 Savage with and without exceeding 46,000 CUP. While is it fun to do this sort of thing, rather than experiment, if I need more gun, I’ll grab the .30-06.
I have many rifles in 300 Savage and therefore can not afford to have in my possession any .300 Savage ammunition that can NOT be used in ALL 300 Savage rifles in my collection. Within the hunting ranges folks can accurately hit when hunting deer a .30-30 is good enough and .300 Savage will exceed that. Except for Grizzly in my part of the country, .300 Savage is all the gun needed in these heavily wooded mountains of Montana.
A Case Comparison, .308 Winchester and .300 Savage
.300 Savage was the inspiration and the parent case for the T-65 experimental cartridge that was an improved .300 Savage case that simply increased the case capacity by 7.4% by decreasing the angle of the shoulder and slightly lengthening the neck to better hold the bullet. It is essentially the same technique used for Ackley Improved cartridges that add case capacity that allows more powder, and thereby increases the potential top velocity without an increase in the maximum working chamber pressure. The difference between the cases is minuscule, yet the increase in performance is worthwhile. Larger cases can produce more velocity or a specified velocity with less pressure. Less pressure is easier on semi-automatics and produces less throat erosion in barrels.
Reloading for a 1891 Argentine Mauser Chamber in .308 Winchester
By downloading .308 Winchester to lower pressures that antique actions can handle and to .300 Savage performance levels we are not giving much up, but can enjoy the lower recoil or a lighter and easier to carry rifle, as we have an appreciably higher performance level relative to .30-30. One of the best ways to find a safe and lower pressure starting load than is listed is to use IMR medium burn rate powders such as Varget, IMR 3031, IMR4895, and IMR4064 and multiply the maximum charge listed for that cartridge from any reloading manual by multiplying the charge weight by .7 (70 percent). This would be the lowest safe starting load with these popular powders. This produces a starting charge that is 30 percent less than the maximum, and lower than listed in most reloading manual and can safely done using these IMR powders and Varget.
With these powders, and possibly other powders not mentioned as the expectations, download all other powders listed by only 20 percent. IHMO, H4895 is the best powder for developing loads in antique, and for proving the rifle to be sound. H4895 is an example of an exceptional exception as it can be reduce by 40 percent and because it is a temperature stable powder. To determine the lowest safe starting charge multiply the maximum charge as listed in a reloading manual by .6 (60 percent).
Here are instructions for a reduced power charge using H4895 as provided by the manufacturer.
See the example loads as found on the American Rifleman website for confirmation and further discussion.
If the reloader would prefer, examine the data available in Lyman 44th reloading manual published in 2002. Download the PDF file for free. I would use .300 Savage data or use the starting loads for cast bullets for .308 Winchester and work incrementally from the lowest pressures to slightly beyond the starting charges for .308 Winchester.
If the reloader is not well practiced at recognizing pressure signs, .300 Savage data has the advantage as there is a wider selection of powders listed and the maximum charges are well under the pressures of .308 Winchester when 300 Savage charges are loaded into .308 Winchester cases. If loading in .300 Savage cases, Lynman’s 44th manual lists pressures in their 300 Savage section that is appropriate for Savage 99 actions that should not exceed 47,000 psi (approximately 44,000 CUP). However their maximum charge weights as listed by other reloading manuals are listed as producing 46,000 CUP (approximately 51,000 psi) and that is why I refer to Lyman’s 44th Edition. Always proceed with extra caution when approaching the maximum listed charges for any rifle.
Reloading Other Antique Mausers in .308 Winchester
With the advent of .308 Winchester and .308 Winchester Service Rifle Data on Hodgdon’s Reloading Center, and in Hornady’s 10th edition both of these are two good sources of data when reloading using .308 Winchester cases if the action is a 1895 Mauser action or later model.
This data is not entirely suitable for 1891 Mauser Actions therefore, to give our selves a wide margin of error and safety, I would use .300 Savage data from Lyman’s 44th Edition and stop at the starting charges for .308 Winchester Service Rifles. Maximum charge weights for 300 Savage loads are less than the starting loads for .308 Winchester Service Rifle or .308 Winchester loads.
For the purposes of hunting, the starting charge in the .308 Winchester Service Rifle data is plenty powerful and easily exceeds .300 Savage levels. However should the rifle be pressed into a counter-sniper role, with the use of certain powders such as H4895, H4350, H4831, Varget, and BLC2, we can continue and approach the maximum pressures and almost attain 7.62NATO M80 and M118 ball ammunition trajectories in 1891 Argentine Mausers with 24 inch or longer barrels rechambered in .308 Winchester (7.62×51) with lower pressure well under the maximum.
We can use the maximum charge weights and powders listed on Hodgdon’s .308 Winchester Service Rifle data that lists data for Varget, H4895, or BLC2 as the maximum charge produces pressures that the 1981 Argentine Mauser action can handle that is no more than 44,000 CUP as stated by Hodgdon. Using 150-grain lead core projectiles, these powders will produce velocities around 2,750 fps if a 24-inch barrel is used.
A maximum load using one of these powders listed by the Hodgdon Reloading Center can duplicate 7.65x53mm 1891 Argentine Mauser performance that is on par with 7.62 NATO. These powders, using Hodgen’s .308 Winchester Service Rifle data will produce top velocities and pressures that are 44,600 CUP or less using bullet weights of 175 grains or lighter. Using projectiles with extremely high ballistic coefficients will further improve the trajectories at low pressures and velocities.
Thankfully, I have plenty of Varget that is a very temperature stable powder. It would be ideal for near maximum loads in my antique 1891 Argentine Mauser action rechambered in .308 Winchester. When pushing towards the maximum pressures of antique actions, I would use only medium and slower burning powders that are also temperature stable. H4831 is so slow-burning that an entire case loaded with H4831 would not blow up the gun. If one day I did not have any way to measure powder charges in terms of grams or grains, or by volume, this is the powder to use. It is a good thing that I have plenty.
(To be continued in Part 5.)