i am a little confused. i looked in the Lyman catalog and found that they sell molds for the 45 colt in both .452 and .454 diameter. the RCBS catalog is the same.

1. why the 2 different diameters?

2. what is the sized diameter supposed to be?

thanks for the help......

Bill: In the old days, the spec for .45 (Long) Colt groove diameter was 0.454", and that was what Ideal made the moulds for. As I understand it, when the .45 ACP came out, the jacketed bullets required less groove depth for grip and to accomodate fouling, so the groove spec. went to 0.452". In recent years, for manufacturing convenience, both .45 LC and .45 ACP have settled on 0.452". So Lyman moulds are found with both designations: e.g., #454190 and #452190. Similarly, .44-40's, which used to be specced at 0.427", (and 'way back when, at 0.424" - you'll still find old Ideal moulds marked "42498") now have their barrels made on the same tooling as the .44Spl./Mag. and the .444 - 0.429"-0.430". It's all sorta moot, as Lyman's tolerances on diameter are farly loose, as-cast diameters vary 2-3 thousandthe with different alloys, and "fashions" in sizing range from groove diameter to 0.003:" or so over. If you're really after accuracy, you'll have to try various diameters anyway to see what your revolver likes - and THAT's assuming you have the right combination of chamber mouth, forcing cone and barrel diameters (and no "squeeze" where the barrel threads into the frame).

floodgate

Bill, I think Floodgate has it about right. I know of a pair of 1917 revolters, one S&W the other Colt. The Colt didn't shoot worth a darn until a .454 boolit was stuck into it. The S&W always worked well with any 'standard' .45 ACP. I think the Colt bbl was a carryover from the good ole days. And the chamber throats would accomodate the .454 passing with finger pressure and the .452 just drop through. I know this isn't .45 Colt, but it gives an idea what Colt was doing way back then and the differences that can be encountered. sundog

thanks, guys. i have a 45 acp mold and i was wondering whether i should try to load some of those bullets in my 45 colt. i guess the bottom line is to just try it and see how it works.

thanks again.........

Bill, Go to the fishing dept. of your favorite sporting goods store and buy some egg sinkers in size 8 [I think]. Rub the edge with a soft lube and slug your cylinder throats with a heavy hammer and a hardwood dowel. [Inverting a gas check of a smaller diameter like .429 helps some in my opinion. Measure your six slugged sinkers with a micrometer and do the same to your barrel. Your Cylinder throats should be slightly larger than your barrel and uniform. That is the diameter to size your bullets to rather they measure .452 or .453. or .454. My ruger throats were 5 different diameters, and all smaller than .451 until they were uniformed improving cast accuracy greatly. Gianni.

Bill,

The other fellows have provided some good information about how these sizes all come about.

Not bad at all. However, you may ponder what size is best for your particualr revolver!

For best understanding of this question you should measure the sizes of both the chambers of your revolver and the barrel groove diameter.

Typicaly the chamber should measure something like 0.453 or more. The barrel, to be compatable, has to be smaller: O.452 or so.

You see, the bullets should bump-up some during firing so that they will fill the chamber throats, seal the gases and then, when the bullet jumps the gap to the barrel forcing cone they will be bigger than the barrel grooves in order to seal off the barrel and prevent leading from gas blow-by.

This all requires a bullet of suitable hardness/softness, depending on the load used.

My 45LC, for example, has chambers of 0.453 diameter and barrel of 0.4525. I feed it fairly soft bullets of 0.455 diameter in "mid-range" loads: Things like 7 or 8 grains Bullseye under the typical 240 grain bullet.

I never, ever get leading with this kind of load. In fact I am able to shoot it virtually indefinitely with no cleaning at all.

Good evening,
Forrest