The Mars automatic pistol, also called the Webley-Mars or the Gabbet-Fairfax, is a British semi-automatic pistol.
The gun was designed in 1897 by Hugh Gabbet-Fairfax. It was originally manufactured by Webley & Scott of Webley revolver fame, then by most other small manufacturers. Production was halted in 1907 after only about 80 were made. Originally supposed to be a possible replacement for the Webley revolver, it was submitted for no less than seven trials, but was rejected every time due to unacceptably high recoil, ridiculous muzzle flash and mechanical complexity; the captain in charge of the Mars actually said "no one who shot once with the Mars wanted to shoot it again". While Fairfax wanted the guns to be put into service, he did not listen to the complaints and fix the problems with the Mars, causing his company to go bankrupt.
The Mars had an interesting feeding system where it pulled cartridges out of the magazine from the rear. Whenever it fired, the whole foreend would recoil back to cycle the weapon, pushing back on the slide. The slide will pull the round out of the chamber and ready it for firing. However, the body design is very unique; every single gun differs slightly from another, as they were all hand-made.
The Mars accepted 8.5mm Mars, 9mm Mars, .45 Mars Long Case and .45 Mars Short Case; all these cases are bottlenecked with large powder charges. The pistols which fired .45 rounds were the most powerful pistols in the world at the time.
As all Mars pistols were hand-made, each pistol was slightly different from each other, as they would lack or have certain components others would not have.