JMB started the High Power for FN but died during its development.
From
http://www.fnhipower.com/
"The specifications were received at Fabrique Nationale in Belgium, with whom John Browning had worked for years. There are some accounts that show that John Browning immediately went to work on a pistol to meet these criteria, while others of the famed FN engineer Dieudonne Saive providing Mr. Browning with the initial high capacity magazine designs. However the beginnings, John Browning produced two models of pistol for the French trials of 1922. Both featured 15 rd magazines and graduated rear sights, but had different operating mechanisms, and were slightly over the weight restriction. The second design, a locked breech and striker fired pistol was the one selected by FN to further pursue the French contract. It was this pistol, with some improvements that was John Moses Browning's last pistol design, the patent being granted in February, 1927 shortly after his death. As Mr. Stevens' Hi Power reference (The Browning High Power Automatic Pistol) mentions, it is interesting to note that while the patent contained many detailed descriptions of the pistols function, nothing is mentioned of the then very exotic high capacity magazines. It was thought that a description of the magazine would aid rivals in their own design pursuits.
The French trials of 1922 led FN's Mr. Saive to further development on a short version of the Model 1922. He dispensed with the striker assembly, and added a hammer and lightened the pistol somewhat. This became known as the Model 1923, and was noted as the finest pistol yet tested by the French during the 1923 trials, though still slightly over weight. Continued development of this pistol, known as the Grand Rendement, found Mr. Saive shortening the slide somewhat, and reducing the number of cartridges from 15+1 to 13+1 in an attempt to bring the pistol's weight to within the French specification. At this point the pistol retained it's original "breech bolt" concept, and had a "stepped" upper slide and was a bit thick in the upper grip area. But the Hi Power's graceful lines were just starting to show in the trigger guard, and front of the slide. Fn actually started marketing this pistol as soon as 1927.
By 1928, Colt's patent protection had run out on the 1911, and Mr. Saive began his third update to John Browning's original design utilizing some of the features Mr. Browning had incorporated into the 1911, but had been unavailable to FN because of the patent time limits. The Model 1928 dispelled completely with the bulky breech bolt assembly, and the the P35 as we know it today was readily apparent with the addition of a 1911 style barrel bushing and a straight grip. By 1931 the pistol featured a curved backstrap and the fixed bushing of today's Hi Power. The pistol was completed and ready for production in 1934, being offered with either a tangent style adjustable or standard fixed rear sight. It was slim, held thirteen cartridges, and was the most advanced military pistol available. Production began, and in May of 1935, Belgium accepted the first 1000 pistol order from FN sealing the Hi Power's designation of Model 1935 forever. With a state of the art design, and the swirling murkiness of events counting down to World War II, The Browning Hi Power stood on the brink of becoming the most widely used military pistol in history."
, take it as you will). So he packed up his stuff and went to Belgium.