Early in the 20th century one of the weakness observed by an inventor named Harald Sunngard in automatic pistols was that during reloads while under stress were often bungled by shooters. This would leave them vulnerable to return fire without being able to shoot back. This Norwegian inventor came up with a solution. There were two parts to this, the first was to use a big magazine, second was to store a spare magazine right in the well of the pistol for immediate use.
The grip of the pistol needed to be big enough to store two identical magazines. One in the front and one in the back inside the well. The front magazine sits higher than the rear one, the bolt face on the slide feeds rounds from the front magazine into the chamber. Once the magazine is empty, shooter ejects it and slide the rear magazine to the front position.
This pistol shoots a 6.5mm and the magazine holds 25, with two magazines the shooter has 50 rounds available. Sunngard hypothesize that while in a gun fight with the common handguns which was only 7 to 8 rounds. While the reload is where Sunngard auto pistol would come into play without a reload and win the gun fight.
The Sunngard pistol was a simple design, uses a plain blowback action, with a no locking system for the small cartridge. The barrel is fixed to the receiver and a recoil sprin is located around the barrel and inside the barrel shroud.
Reports has it that Sunngard tried to market the pistol to military forces, but was not successful. There was a story that in the Norwegian military trials that it was tested against the Colt 1911, unfortunately no records of the results. Which would have been interesting to see. Some of the many reasons as to why the pistol never made it big, may be due to its low cartridge power and the reloading was awkward.
Caliber: 6.5mm (also 8mm)
Cartridge: 6.5mm Sunngård (6.5x19mm) (also 8x19mm)
Bullet weight: 28.5 gr (1.85g)
Overall length: 8.0in (203mm)
Barrel length: 6.2in (158mm)
Height: 5.3in (135mm)
Weight unloaded: 26.8oz (760g) (28oz/800g for the 8mm variant)
Weight loaded: 33.8oz (960g)
US Patent 972,087 (Harald Sunngård, “Automatic Firearm”, October 4, 1910)
Source: Wikipedia, PopularMechanic, Ian McCollum