Howdy: Which is the best load development software out today? Something that would provide estimated pressure, velocity, etc. Components IMR Trail Boss powder .455" 250gr Remington swaged LRNFP bullet Large Pistol primer .45ACP brass Purpose Stoke my Webley MK VI (with shaved cylander) with a low-pressure load that comes close to the .455 Webley load of 265 LRNHB bullet at ~650fps. Why These Components? I already use Trail Boss in .357mag & .44mag, have plenty of .45ACP brass. The Remington .455 250gr swaged LRNFP are about the cheapest bullets that have been know to work well in the Webley MKVI. ---------- I guess the day had to come. I want to shoot a powder/bullet/primer combination for which there is no data. I would like some sort of sanity check before I start putting components together and I hope to use such software in addition to the 10 or so reloading manuals I own. I am familiar with IMR's online load data. I own a chrony and know how to use it as a further check. ---------- The Virginian at http://forums.handloads.com/forum_posts.asp?TID=10340&KW=webley+1917 has developed a similar load using (not Universal) Clays. I have no desire to use yet another quick-burning powder.