This week I am casting bullets for my Colt New Service .455 Eley from the new Accurate mold 45-264H, to load in my newly received Starline .455 Mk2 cases.
Starline .455 Mk2 brass is 0.76" long, vs. 0.86" for Dominion .455 Eley and .455 Colt cases.
Accurate 45-264H was designed with the absolute minimal 0.25" seating depth, to maintain powder capacity and reduce pressure in the shorter case. It also features a 0.1 wide, full-diameter front driving band above the crimp groove. This aids cartridge alignment in the chambers when using the shorter Starline, Fiocchi and Hornady Mk2 cases in longer Webley military and Colt New Service revolvers manufactured with long chambers intentionally dimensioned for the longer Mk1 (Colt-Eley) case, so that those WW1-era revolvers could fire either round.
The shorter Mk2 case was adopted in 1897 to reduce excess free airspace in the case to improve ballistic uniformity when used with smokeless powder. The correct powder charge to use in Mk2 Starline cases with this bullet is 3.5 grains of Bullseye. This matches the 625+/- 25 fps velocity of the WW2 era Mk2z service load, an example Kynoch (1942) FMJ load being shown in the photo below, at left.
The center ctg. in the photo is a .455 Eley with Accurate 45-290H bullet assembled in a 0.86" case, made by shortening Starline .45 Schofield brass to 0.87" and lathe-turning the rim. If this heavier bullet is to be fired in Webley top-break revolvers it should be loaded ONLY in the longer 0.87" case, UNLESS the powder charge is REDUCED to 3 grains of Bullseye. In the longer 0.86" length case which was pressure tested by Larry Gibson, the maximum recommended charge is 3.5 grains of Bullseye, which should not be exceeded.
Making the longer Colt-Eley-Mk1case from Schofield brass is recommended for those loading ammunition for older marks I through III of Webley revolvers which are proved for black powder only, so as to hold the full 21 grain black powder charge.
But for most users of Boer War era Webley MkIV and later Webleys, as well as the S&W .455 Hand Ejector and Colt New Service, buying Starline Mk2 cases is very much easier. This new Accurate 45-264H design mostly compensates for the shorter Mk2 case by reducing bullet seating depth to maintain powder capacity, reducing bullet jump and improving guidance of the bullet in its transition from case mouth to the cylinder throat. The large meplat will provide good crush characteristics with deep, straight-through penetration, at low velocities <700 fps where no expansion is expected.
My mold drops bullets as-cast from 12 BHN backstop scrap at .456" diameter and 262 grains. It fits my 1914 Colt New Service as-cast and unsized. The .425" long nose above the crimp precludes its use in the .45 Colt, as cartridge OAL would be 1.71". Cartridge OAL is 1.525" in .45 Schofield brass, 1.323 in .45 Auto Rim, 1.285" in .455 Colt and 1.185" in .455 Mk2, and this ogival wadcutter should have excellent potential for those classic .45s.
Attachment 235998Attachment 235999