A Question on .455 Conversions

delta-419 · #1 10-22-2016, 07:07 PM

I know that many .455 Triple Locks and MKIIs were converted from .455 to 45LC at some point in time as the 45 Colt is much more popular in the U.S. My question for those of you who shoot these conversions is: what accuracy can be had, given the barrel diameter. The 45LC is .452 while the barrel is .455 or more. This is a project gun question as I just came into possession of a very excellent .455 barrel and can build a 45LC around this caliber. What say you!

Muley Gil · #2 10-22-2016, 08:06 PM

Back in the '70s, I had a 2nd model .455 that had been converted to .45 Colt. I loaded it with a Keith 255 gr SWC over 7.5 gr of Unique. Due to the length of the cylinder, I had to deep seat that SWC and crimp over the front band. The bullets were cast by me and sized to .452".

It would group 3" and under, at 25 yards, if I did my part.

DWalt · #3 10-22-2016, 08:16 PM

The only answer is for you to shoot it yourself from a steady rest and see how well or how poorly it groups. Soft lead bullets will expand a little under pressure of firing and fill the groves. Even if the bullet is 0.002-0.003" undersize, the lands will still bite into the bullet. And then there is the question of the propellant and charge weight. Some charges will always shoot tighter groups than others. My guess is the .455 barrel can be made to do what you want it to do.

For a long time, I used standard .357-.358" diameter .38 Special lead bullets for reloading the .38 S&W, which has a nominal groove diameter of .360-.361". They grouped very well.

Skeetr57 · #4 10-22-2016, 09:08 PM

The original bore and bullet diameter for the .45 Colt was .454" until sometime after WWII, so it should have the correct bore diameter for the .454 diameter lead bullets that are used when reloading for older Colt guns.

DHENRY · #5 10-23-2016, 04:39 PM

Like Muley Gil, I reloaded with those Elmer Keiths (back when I had a 455-to-45LC conversion TL).
Strangely, accuracy was just as good with 'cowboy action' RNFP factory ammunition (!).
Both were about as good as the open/blade sight combo was capable of.
Don

Hondo44 · #6 10-23-2016, 05:03 PM

Pre war Smiths with 45 Colt chamberings were so few, Smith used the same groove and bore sizes as their .455 cartridge chamberings as follows:
groove diameter--.457' to .458"; bore diameter--.447" to .448";

This does not pertain to the 1917 45 ACP barrels or post war and current Smith .45 Cal barrels which have:
groove - .451", bore - .445".

Therefore 45 Colt shoots quite well in 455 barrels. Some use .454" sized bullets, but as reported above .452" bullets seem to work just as well. So off the shelf .45 ammo works well. If you hand load, I recommend sizing your bullets appropriately for the chamber throats of whichever cyl you use.

By the way, only the British referred to the 455 2nd Models as Mk II revolvers (and stamped them as such on the left side of the frame).

All three 455 Models made by Smith were chambered for the longer 455 Mk I cartridge. Smith's caliber roll marking (when marked) only refers to the 455 Mk II cartridge for all three models.

Hondo44 · #7 10-23-2016, 08:13 PM

I have a 455 Triple Lock barrel and will do the same if I ever find a 2nd Model 455 or 1917 host gun sufficiently unoriginal for a project. The middle or 3rd lock will of course be functional.

I will rechamber the cyl for the very 1st TL cartridge, the Army Trials prototype cartridge ".45 S&W Special" AKA ".45 Frankford Arsenal (Cal. .45 Ball, Model of 1906". 0.923" case length. Just for tradition's sake.

If I start with a 1917 cyl it will still chamber and shoot the 45 AR and 45 ACP (but only with clips).

If I start with a 455 2nd model it will still chamber and shoot 455 Mk I/Mk II.

DWalt · #8 10-23-2016, 11:57 PM

I shoot .452" lead bullets in an early Colt New Service (M1909) in .45 Colt. The original Frankford Arsenal bullet diameter specification was .455" but the .452" bullets work very well in it. I just loaded 100 of those this afternoon.

"I will rechamber the cyl for the very 1st TL cartridge, the Army Trials prototype cartridge ".45 S&W Special" AKA ".45 Frankford Arsenal (Cal. .45 Ball, Model of 1906". 0.923" case length. Just for tradition's sake."

To assist in making your M1906 load more authentic and original, the original M1906 Frankford Arsenal cartridge used a 230 grain cupronickel FMJ bullet (made with both .453" and .450" bullet diameters) and 7.2 grains of Bullseye powder. The Arsenal drawings make it look as though the bullet has a hemispherical nose, but I don't know what the actual shape was. I suppose a .45 ACP FMJ bullet would be about as close as you could get to the original.

Muley Gil · #9 10-24-2016, 04:58 AM

"the original M1906 Frankford Arsenal cartridge used a 230 grain cupronickel FMJ bullet (made with both .453" and .450" bullet diameters) and 7.2 grains of Bullseye powder."

I just checked my 45th Lyman reloading handbook. The max Bullseye load for a .45 Colt with a 235 grain cast lead bullet was 6.8 grains.

Don't think I'd use that gov't load!!!!!

jaymoore · #10 10-24-2016, 05:09 AM

I used to utilize the Winchester 255gr Swaged lead RN, hollow based bullets for my various .455s with good results. Not only did the hollow base accommodate large variations in throat and groove dimensions, they were manufactured with a 0.456" O.D.! Only have a couple boxes left after all these years, have been using an old Lyman 454424 mould mostly for some time. Not quite as good, but fine for recreational use.

DWalt · #11 10-24-2016, 08:12 AM

Quote:

Originally Posted by Muley Gil

"the original M1906 Frankford Arsenal cartridge used a 230 grain cupronickel FMJ bullet (made with both .453" and .450" bullet diameters) and 7.2 grains of Bullseye powder."

I just checked my 45th Lyman reloading handbook. The max Bullseye load for a .45 Colt with a 235 grain cast lead bullet was 6.8 grains.

Don't think I'd use that gov't load!!!!!

The Bullseye powder of that time is not the same as the canister Bullseye of today. Bullseye has always been a blanket name covering several varieties made by Hercules for use by the loading companies, such as Bullseye #1, etc. in order to provide an array of relative quickness in burning rate to meet specific ballistic performance needs. I think that which was sold for canister sale to reloaders was known in the industry as Bullseye #3.

Hondo44 · #12 10-24-2016, 02:50 PM

I don't own any Bullseye anyway because I don't use it. Too fast burning and too easy to double charge.

Tom K · #13 10-24-2016, 03:05 PM

In this post I shot a couple of .455s converted to .45 Colt, one Triple Lock and one 2nd Model HE. You'll have to judge for yourself whether the grouping (good or bad) is due to the gun or the shooter.

At the range with .45 Colts, .44 Specials