Nonsense. The profit margin on gov't issued/gov't contract firearms is not very high, and that's if they aren't sold at a loss. Glock being able to say, "The FBI issues Glocks" results in a lot of retail sales of Glocks to civilians.
Of their "leading brands of handguns"; Glock is Austrian, Sig Sauer is German, Beretta is Italian, and Colt is bankrupt. They would tell Obama to pound sand. Sturm, Ruger & Company and Smith & Wesson previously drank the gun control Kool-Aid and it just about destroyed their sales. (Colt also did and it helped bring them to Bankruptcy Court, along with a lot of other bad management decisions.)
Government is also a notoriously slow paying customer.