If the barrage costed 40muni...
i'd spam it till the day is done
The barrage is free now though? A muni cost would further devalue the unit. Are you thinking of the Zis barrage? That costs 60 munis.
I say - decrease fuel to 50-60 (70 is too high) and make it a little better at hitting infantry with its normal attack, e.g. a larger splash on the shot. Make the barrage a little more accurate. too.
Alternately, make the main gun do a little better against medium tanks?