Cast bullet loads usually give a more useful zero at practical field ranges with military battle sights than do full power loads. Nothing is more frustrating than a military rifle that shoots a foot high at 100 yards with surplus ammo when the sight is as low as it will go! Do not use inert fillers (Dacron or kapok) to take up excess empty space in the case. This was once common practice, but it raises chamber pressure and under certain conditions contributes to chamber ringing. If a particular load will not work well without a filler, the powder is not suitable for those conditions of loading. Four load classifications from Mattern (1932) cover all uses for the cast bullet military rifle. I worked up equivalent charges to obtain the desired velocity ranges with modern powders, which provide a sound basis for loading cast bullets in any post-1898 military rifle from 7mm to 8mm
The "100 Yard Target and Small Game" Load
I use Mattern's plain-based "100 yard target load" to use up my minor visual defect culls for offhand and rapid-fire 100 yard practice. I substitute my usual gas-checked bullets, but without the gas-check. I started doing this in 1963 with the Lyman #311291. Today I use the Lee .312-155-2R, or the similar tumble-lubed design TL.312-160-2R. Most of my rifle shooting is done with these two basic designs.
Bullets I intend for plain based loads are blunted using a flat-nosed top punch in my lubricator, providing a 1/8" flat which makes them more effective on small game and clearly distinguishes them from my heavier gas-checked loads. This makes more sense to me than casting different bullets.
Bullet preparation is easy. I visually inspect each run of bullets and throw those with gross defects into the scrap box for remelting. Bullets with minor visual defects are tumble-lubed in Lee Liquid Alox without sizing, and are used for plain base plinkers. Bullets which are visually perfect are weighed and sorted into groups of +/- 0.5 grain for use in 200 yard matches. Gas checks are pressed onto bullet bases by hand prior to running into the lubricator-sizer. For gas-check bullets loaded without the gas- checks, for cases like the .303 British, 7.62 NATO, 7.62x54R Russian and 30-06, I use 6-7 grains of almost any fast burning powder. These include, but are not limited to Bullseye, WW231, SR-7625, Green Dot, Red Dot or 700-X. I have also had fine results with 8 to 9 grains of medium rate burning pistol or shotgun powders, such as Unique, PB, Herco, or SR-4756 in any case of .303 British or larger.
In the 7.62x39 case, use no more than 4 grains of the fast burning powders mentioned or 5 grains of the shotgun powders. Theses make accurate 50 yard small game loads which let you operate the action manually and save your precious cases. These plinkers are more accurate than you can hold.
Repeated loading of rimless cases with very mild loads results in the primer blast shoving the shoulder back, unless flash holes are enlarged with a No. 39 drill bit to 0.099" diameter. Cases which are so modified must never be used with full powered loads! Always identify cases which are so modified by filing a deep groove across the rim and labeling them clearly to prevent their inadvertent use. For this reason on I prefer to do my plain based practice shooting in rimmed cases like the 30-30, 30-40 Krag, 303 British and 7.62x54R which maintain positive headspace on the rim and are not subject to this limitation.
