A large‐volume (6‐liter) electron‐beam‐controlled discharge of about 1 &mgr;sec duration in a Xe/Ar mixture with HCl as the chlorine donor has been utilized to achieve efficient XeCl laser generation at 3080 A˚. At a fixed gas pressure and e‐beam current, the laser output is found to increase rapidly with the initial sustainer field strength up to the spontaneous breakdown limit. Near such a limit, a factor‐of‐25 enhancement of the XeCl laser output energy over that due to e‐beam pumping alone has been observed at 1 atm total pressure. The specific output pulse energy density and laser efficiency based on total energy deposition, of 0.5 J/liter atm and 0.7%, respectively, are beginning to approach the best values reported in the literature for the XeF and KrF lasers.