The Swiss were the first country to adopt a self-loading service pistol; the Luger in 1900. They would keep those in service clear through World War 2, at which point they began seriously looking for a more economical and more modern replacement. During the 1940s, a number of experimental designs were developed at the SIG and W+F Bern factories in hopes of becoming the new Swiss service sidearm.
This example is a P47, one of 10 guns made in 1947, at the end of W+F Bern’s developmental series. While the preceding guns had been largely based on the Browning High Power, the P47 was a gas-delayed blowback action similar to the H&K P7, Norinco 77B, and Walther CCP (although predating all of those). Its barrel had gas ports just in front of the chamber which led into a gas piston that acted to hold the slide in battery when pressurized. Thus the slide was delayed from opening until the bullet has left the muzzle and gas pressure had dropped enough for the recoil spring alone to safely control the opening of the action.
Unlike Bern’s previous experimental pistols, these 10 P47s were all identical (and have serial numbers in the low/mid 40s to low/mid 50s). I had a chance to shoot one of these (serial number 46), and it was a pleasant enough piece, although in my experience the gas delay system did not provide a substantial improvement over what was ultimately adopted by Switzerland, the SIG P210.