45 acp brass with 45 colt boolits for webley mk VI

[Dustin]

I am trying to figure out the best load for my webley mk VI. Eventually I want to get auto rim brass so I don't have to use moon clips but I have a supply of acp brass now. if I get a mold for a 255gr 45 colt boolit do I have to seat it in the 45 acp brass with a colt die or will the acp seater work. whats the best powder load and anything else I could use.
all info will be much appreciated thank you.

[Outpost75]

You want to keep the loads lighter than full .45 ACP loads, because the .45 ACP is loaded to about 20,000 psi, whereas the .455 cartridge for which the revolver is designed is about 14,000 psi, similar to the .45 Colt.

The only reason people got away with shooting factory jacketed .45 ACP ammo in these guns is because the jacketed bullets were undersized and you got alot of gas leakage around the bullet, so the cartridges never built to full pressure, and velocity dropped with hardball to about 700 fps, vs. 830 fps in a comparable .45 ACP revolver like an S&W M1917 Military or Colt New Service.

If you use lead bullets which fit, and drive them to full .45 ACP velocity you are shooting the equivalent of proof loads every time you pull the trigger and you will pre-maturely wear out a nice old gun.

In my Boer-war era MkIV revolver I stick to .455 equivalent loads, not exceeding 3.5 grains of Bullseye with the Saeco #955 260-grain bullet, cast of wheelweights and loaded as-cast and unsized at .455", tumbled in Lee Liquid Aliox. With the 230-grain Saeco #954 I do not exceed 4 grains of Bullseye. These are fun to shoot and accurate.

Save your thunder bumper loads for major caliber IPSC. If you want your Webley Mark VI to last, shoot the equivalent of Cowboy loads in it.

[plainsman456]

I loaded up some with trailboss.
If you can find some they are a fun shoot.

[Bigslug]

My first MKVI is a .45 ACP conversion like yours. I bought the RCBS mold that replicates the original 265 grain HB, and ran into the conundrum of needing a powder that would fill the larger-than-.455-Webley space without exceeding .455 Webley pressures.

3.0 grains of Trailboss nicely did the trick.