45 Colt cast bullets what diameter?

[Mr Humble]

I have a new Ruger BH and a 1926 Colt New Service Flat Top Target.
Every article I read in the 45 Colt and cast bullets gives conflicting information.
I have seen everything from .451 to .455. Most of the articles appear to address issues where the cylinder throat and barrel don't match up. I already have .452 molds and sizers for the 45 ACP. These are both just "fun guns" as I have a S&W 329 44 Magnum for serious work.
Thanks!

[45 2.1]

I have a new Ruger BH I measured one a month ago with 0.453" cylinder throats and 0.452" barrel groove. The guy who bought it uses the Lee 255 RF boolit sized in a 0.454" sizer to just lube it. His boolit measures about 0.4525". and a 1926 Colt New Service Flat Top Target. The New Services I shot and owned all liked 0.454" boolits, specifically the 454190 Lyman.
Every article I read in the 45 Colt and cast bullets gives conflicting information. The specs changed around WW2. Basically they went from 0.454" nominal to the modern 45 ACP barrel standards of 0.451" to 0.452" nominal.
I have seen everything from .451 to .455. Some go 0.457" in the older S&W revolvers. Most of the articles appear to address issues where the cylinder throat and barrel don't match up. Or are reversed with a smaller throat than barrel groove. I already have .452 molds and sizers for the 45 ACP. These are both just "fun guns" as I have a S&W 329 44 Magnum for serious work.
Thanks!

[missionary5155]

Good afternoon
I check every new gun to me. I trust no factory. They may work within the limitations of specs.. but I wonder what specs they are reading.
Ruger has even found the way to undersize 41 Mag chambers...
So my advice is to get some pin guages and an accurate micrometer. This will certainly save you some consternations over the years as you work with revolvers.

[Sagebrush Burns]

Supposedly "modern" 45 Colts have .451 bores and pre-war guns have .454 bores. In the guns I have (all modern Colt SAAs and various Rugers) I have tried both .454 and .452 bullets and have not found it to make any difference that I can tell. Of course I may not be a consistent enough pistol shooter to really make that call.

[spqrzilla]

My Ruger Blackhawk has .452 cylinder throats. That's what I size to.

[9.3X62AL]

Lotta good info above. There was a time that Ruger BHs came with .449" throats and .452" grooves (like my 1995-vintage BisHawk did). I finished building the revolver by reaming and honing the throats to .453", and now run .454" castings with GREAT accuracy. I use WW metal for the 800-900 FPS-class loads, and 92/6/2 for the heavier loads. Lymans #454190, #454424, and the GC #454490 all shoot well, as do the Lee 200 SWC target boolits at 800 FPS. Before the throat work, the ONLY bullet/boolit it would shoot at all was the #454490.

[Dale53]

My "new last fall" SS Ruger Bisley .45 Colt/.45 ACP convertible had both sets of cylinder throats undersized (.449"-.451" as I remember). At any rate I had to ream both cylinders to .4525" and now everything works as it is supposed to. I size my cast bullets at .452", get EXCELLENT accuracy and NO leading whatsoever.

When dealing with revolvers, it pays to (each and every time you get a new revolver) slug each cylinder throat and act accordingly.

FWIW
Dale53

[Char-Gar]

Currently I own two revolvers in 45 Colt. A Gary Reeder custom Ruger BH with cylinder throats of .454 and a 1926 Colt New service with cylinder thoats of .455. I use .454 bullets in both.

One other Ruger BH had throats of .451 which I had opened up to .453. I recently gave it to my son. .454 bullets worked just fine in it as well.