That is not the smallest true .45 auto ever created, there is one smaller. The Semmerling LMX. Originally contracted for Army special Ops the LMX was thought for many years to be a myth. The simple fact is that they were designed and completely hand built by the same genius that created the Semmerling LM4. The firearm, along with a complete (and astonishing!) collection of Semmerlings was gifted to the National Firearms museum just a year ago. Those that visit the museum will be able to see an LMX.
The firearm uses the incredibly rare "strip forward" methode to cycle rounds. The friction of the bullet traveling down the barrel actually cycles the slide (returned to battery through an ingenius spring system). The LMX also has a threaded barrel (and required slide lock for absolutely silent shots) for those silent ops times. All this and its the same size as the LM4. The contract was fullfiled and the gun is one of America's rarest and most unusual .45s.
Lastly, the designer always knew that the LM4 could have been originally designed as an auto loader. But there were two important reasons why he chose not to make the Semmerling LM4 an auto loader. First, the Semmerling LM4 was designed as a back-up weapon solely. As most operatives would instinctively know, most back-up situations are when one is looking down the barrel of their own weapon and those kind of conflicts rarely lasted past a single shot. The task is to make that shot 100% fail safe and deadly. Many confuse a back-up weapon with a primary. Secondly, being a superb engineed, he knew that the resulting kick from firing a .45 with such small mass would be just what it turned out to be...a real eye opener! Still, the Army wanted the smalles automatic loader .45acp they could have for their suppressors....they got it. Yes, its a double action too!
Enjoy the picture.