Reloading a Revolver or Automatic

[LBEE]

How does a person know what size bullets to buy for a 45acp verses a 45 revolver when buying bullets. I have read somewhere I think that the .452 are for automatics where the 451 are for revolvers. I dont know for sure if Im correct. I also reload 9MM for a auto which size for them should I be buying?
I have been reloading for over 40 years for Rifles, just started reloading for
a 45ACP & a 9MM auto. Thank you in advance for any help or advice.
LBEE

 

[ku4hx]

45 ACP jacketed are usually .451"; commercially cast are usually .452". But as is the usual case, you can find other diameters. I have seen jacketed at .450" and .452".

9mm jacketed are generally .355"; cast is often .356" to .358" (sometime larger) depending on what the gun needs and the chamber will allow. Commercial cast 9mm is generally .356".

Most loading manuals tell you what diameter bullet they used. Those of us who cast our own often slug our bores to determine actual bore diameter.

 

[SunnySlopes]

I have read somewhere I think that the .452 are for automatics where the 451 are for revolvers

For most applications, does the .001 difference really matter?

 

[Steve C]

Old single action .45 Colts used to have a larger bore diameter of .454 so the typical lead bullets needed to be of greater diameter or .455. The .45 ACP always has had a bore diameter of .451 so the jacketed bullets used where usually .451 in diameter and lead bullets at .452 or .001 over bore diameter.

Manufacturers pretty much standardized on the .451 bore diameter for both the old .45 Colt and the ACP for modern manufacture likely some time in the 1950's and on.

If you want to know the bullet diameter to use for a particular caliber use the loading manual as the guide. Currently the bullet manufacturers like Speer, Hornady, Sierra, etc. use a .451" diameter jacketed bullet for both the ACP and the Colt. Lead bullets from these companies are .452".

If you cast your own lead bullets or order custom cast bullets where you can control the bullet diameter by choosing your post cast sizing then the best way to determine bullet size is to slug your bore and size to .001 over bore diameter. Typically this will be .452 but with some some guns it may be larger.

For most applications, does the .001 difference really matter?

If you choose undersized lead bullets you will get leading from gas blow by since the bullet will not seal in the bore. Jacketed bullets do not have this problem but a significantly undersized bullet will rattle down the bore and you will loose accuracy.