Operating characteristics of a self-heated longitudinally excited Ca+ afterglow-recombination laser (λ=373.7 nm) of large bore (25 mm, active volume 160 cm-3) are described for both constant pulse repetition frequency (prf) and burst-mode operation. Laser pulse energies of up to 1.2 mJ are obtained, which correspond to specific output energies of up to 7 μJ cm-3. Optimum prf for maximum average laser power is reduced compared to small-bore devices, and decreases for increasing buffer-gas (He) pressure. Maximum average power observed was 0.37 W at 365 Hz. Limitations to average-power scaling are attributed to the onset of radial effects.