On the W/R use of Mauser actions; most Westleys (not all) were built on military actions, so the .318 and .425 especially were designed for use in standard mil actions that were then modded to the cartridge by W/R. Thus, we see the rebated rim on the .425 for use with standard bolts and we see the magazine rails on standard actions for the .425 on early models. This was W/R initially having to work around not having access to magnum actions but I believe it also allowed them to market a big game magazine rifle without having to go through (pay) Rigby or Mauser, with surplus mil actions more readily available.