Sentry is turret mode, did you mean Recon at first?
Damage isn’t really his limiting factor, it’s his spread. If his spread were smaller, he could kill tanks much easier because he could actually hit his shots instead of missing 70% of them at 35 meters (source. Technically he would hit more than that because tanks are bigger, but it’s probably fairly close)… I’d much rather have lower consistent damage than larger inconsistent damage…