M1911 pistols were often stolen from NG armories, along with BARs, M1903 rifles and some TSMGs. TSMGs were also bought on the open market, though they were so expensive that (contrary to some belief) not every tiny gun shop had hundreds of them on the rack. Colt GM's also turned up, but as in the rest of civilian life, .45 pistols were not common, and revolvers still were the handgun of choice on both sides of the law.
The Browning A5 and copies were common, along with pump shotguns.
Browning (FN) pistols were almost unknown in the U.S. in that era, since Colt and FN had an agreement where Colt didn't sell in Europe and Africa and FN didn't export to North and South America. They shared the Asian market.
Jim