I’ll give you several.
A catalog for speer rifle bullets...any one will do
A catalog for hornaday rifle bullets...any one will do
A book with exact dimension and drawings of rifle cartriges...title: “Modern Sporting Rifle Cartridges”, by Wayne Van Zwoll.
The british, russian, and japanese 30 calibers are roughly equivalent(.311 or .312) and can be interchanged with eachother, but NOT with the american 30 calibers, which are usually .308.
Additionally, you can look up these calibers on wikipedia and see the case, bullet, and cartridge dimensions there.
30-06 springfield
308 winchester
7.62 NATO
30-30 winchester
30 carbine
300 savage
30-40 krag
307 winchester
300 winchester magnum
300 weatherby magnum
Then compare those bullet diameters to these:
7.62x54R
7.62x39
303 british
7.7 jap(aka 7.7x58 arisaka)
With regret, I am completely lost.
I will restate the facts as I know them and that will be about as much as I can do.
I own an Ishapore Enfield chambered in (American).308 Winchester (7.62 Nato) whose projectile(bullet) diameter is .308
I understand the British .303 projectile (bullet) is .311 diameter and cannot be fired in my rifle.
That said, in the Speer Reloading Manual for Rifle and Pistol #12 in addition to the .311 diameter projectiles (bullets) to be loaded into the .303 British case, there is also a propriatory projectile(bullet)- the Speer Plinker(tm) in diameter .308 on page 330 also to be loaded into the .303 British brass case.
I am unable to find any rifle projectile (bullet) diameters in .309 or .312
Those diameters (.309 and .312) seem to be considered pistol calibers and are listed under 32 S&W Long, 32 H&R Magnum etc.
I have no explanation for any of this, I state the facts as they exist in my corner of the universe and as they can be found in the Wikipedia Article on Caliber.
Best regards,