I always load up a few "squirrel poppers" and keep them handy ... a 0.310 round ball in a case with 2 grains of Clays, then dip it in LLA after loading the round. Super quiet, the ball hitting the target is louder than the report of firing. But I think the questions you're asking were best answered by Mr. Ed Harris.
Cast Bullet Basics For Military Surplus Rifles
By C.E. Harris Rev. 9-6-93
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 a hundred 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 the 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 7 mm to 8 mm:
1. 125-gr., plainbased "small game/gallery"
900-1000 f.p.s., 5 grains of Bullseye or equivalent.
2. 150-gr. plainbased "100-yd. target/small game",
1050-1250 f.p.s., 7 grs. of Bullseye or equivalent.
3. 150-180-gr. gaschecked "200-yard target"
1500-1600 f.p.s., 16 grs. of #2400 or equivalent.
4. 180-200-gr. gaschecked "deer/600-yard target"
1750-1850 f.p.s., 26 grs. of RL-7 or equivalent.
None of these loads are maximum when used in full-sized rifle
cases such as the .30-40 Krag, .303 British, 7.65 Argentine, 7.7
Jap, 7.62x54R or .30-'06. They can be used as basic load data in
most modern military rifles of 7 mm or larger, with a standard-
weight cast bullet for the caliber, such as 140-170 grains in the
7x57, 150-180 grains in the .30 calibers, and 150-190 grains in
the 8 mm. For bores smaller than 7 mm, consult published data.
The "Small Game or Gallery" Load
The 110-115-gr. bullets intended for the .30 carbine and .32-20
Winc
hester, such as the Lyman #311008, #311359 or #311316 are
not as accurate as heavier ones like the #311291. There isn't a
readily-available .30 cal. cast small game bullet of the proper
125-130-gr. weight. LBT makes a 130-gr. flat-nosed, GC bullet
for the .32 H&R Magnum which is ideal for this purpose. I
recommend it highly, particularly if you own a .32 revolver!
The "100-Yard Target and Small Game" Load
I use Mattern's plainbased "100-yard target load" to use up my
minor visual defect culls for offhand and rapid-fire 100-yard
practice. I substitute my usual gaschecked bullets, but without
the gascheck. 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 plainbased loads are blunted using a
flatnosed 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 gaschecked 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-based plinkers. Bullets which are
visually perfect are sorted into groups of +/- 0.5 grain used for
200 yard matches. Gaschecks pressed onto their bases by hand
prior running into the lubricator-sizer.
For "gaschecked bullets loaded without the gascheck," 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 pistol powder,
including, but not limited to Bullseye, W-W231, SR-7625, Green
Dot, Red Dot, or 700-X. I have also had fine results with 8 to 9
grains of medium burning rate pistol or shotgun powders, such as
Unique, PB, Herco, or SR-4756 in any case of .303 British siz
e 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. These
make accurate 50-yd. 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 reloading 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 to 0.099" diameter. Cases which
are so modified must NEVER be used with full-power loads! ALWAYS
identify cases which are so modified by filing a deep groove
across the rim with a file and label them clearly to prevent
their inadvertent use. For this reason I prefer to do my
plainbased practice shooting in rimmed cases like the .30-30,
.30-40 rag, .303 British and 7.62x54R which maintain positive
headspace on the rim and are not subject to this limitation.