I've been shooting and reloading for my 1918 Webley MKVI as the pistol in my club's vintage bolt action matches (pistols must be vintage just as the rifles) for several years. Mine is stamped 6 tons (pressure). The British use long tons, 2200 lbs. which translates to 13,200 psi. A buddy of mine is a gunsmith and showed me a MKVI blown up shooting .45 ACP factory ball ammo which has determined my cautious reloading practice. My loads are kept well below the 6 ton pressure using .455 data with either Berry's plated 45 Colt, 255 bullets or my buddy's 260 cast bullets with any suitable powder (700X, Tite Group, etc.) making sure the velocity of 600-650 fps holding the pressure at or below 10,000 psi. This bullets at this velocity hit point of aim at 25 yds. Great pistols, great history, and mild accurate shooting. I use moon clips as well as auto rim brass but use moon clips for matches (I don't want to lose my auto rim brass). Good luck and have fun.