.358+
As our
freid freind good bud Coffin posts -
but that is "nominal dims"
If you are concerned about actual dimensions, you will probably want to number & slug each chamber mouth.
Then one will probably want to keep a load log including powder, lot #, charge, lead hardness, sized bullet diameters,
day, date, time, temperature, relative humidty, barometric pressure, wind direction and veloicty, altitude, gps location,
sighting methods, standing, sitting, prone, eyeglass prescription, and where one placed ones tongue (left corner of mouth, etc)
Oh, and whether one made a chicken offering to the powder gods.
I myself have had very good luck just using "as cast" soft lead or "wheel weight" lead out of my one RCBS 158 gr swc
and my many Lee .357 molds.
good luck & keep us posted.
ps (in case you could not tell, the above a a jokoe son! a joke! ... Foghorn Leghorn, Warner Bros, ca 1963)
pps - oh, and Pictures Please! love to see the Thunderthing and your chosen bullets!
yhs
prof marvel