Why two .45 caliber diameters?

[mkl]

Does anyone know the reason most .45 caliber handgun bullets measure .452" while most .45 caliber rifle bullets measure .458"?

Just curious, but would be nice if I could use my .45 Colt and ACP bullets in my .45-70 for plinking.

I'm sure that there is some historical reason, but I've never heard it.

 

[AJC1]

The older black powder rounds were 458. The new kid on the block is 45 acp which is 452. Now manufactures do both and I wished they had stuck with 1 size just like the 44 issue. The only one that I know for sure that's the same is 357. I havent checked 41 or the others.

 

[Jim Watson]

Entirely different ancestry.
The .45 handguns are descendants of the .44 cap and ball, originally .454" in LC, later reduced to .451" to match .45 Auto.
The US .45 rifles began with the .45-70. By the time it got into commercial production at Winchester, it was taken as a .450" bore, .004" grooves, .458" groove diameter/bullet.
Pistol bullets will not be satisfactory in a rifle.

 

[Walkalong]

Just curious, but would be nice if I could use my .45 Colt and ACP bullets in my .45-70 for plinking.

I bought some "over run" .300 Gr .452 bullets that make nice plinkers in my .458, but I have to size the case with the .458 sizer, then use my .45 Colt sizer to size just enough of the top of the case to get good neck tension. Works though.

 

[earlthegoat2]

I think it is good to have delineation between bullets for rifles and bullets for handguns.

It is the same way with .358 rifle bullets and .355-.357 handgun bullets. Those can be mixed and matched to a small extent.

 

[buck460XVR]

Does anyone know the reason most .45 caliber handgun bullets measure .452" while most .45 caliber rifle bullets measure .458"?

Why are most jacketed bullets for use in .45ACP .451, when those bullets intended for .45 Colt are generally .452? Why do I use .452 bullets in my .454 and .460? Why do my .357 magnums use a .357 bullet, but my .44 magnums use a .430 bullet? Why is it my 450 cc dirtbike is not really 450 cc?

I think some folks just like to keep us cornfused........