First thing to try is extending the TimingBudget. A 4X increase in TB will double the accuracy.
You can also average several ranges together to eliminate noise, but it depends on your expected rate of change. I've had good luck with running averages.
The sensor is going to average all the photons it gets back. So if your object is near enough and the return signal is strong, you might consider reducing the Field of View. This will cut down on the photons coming from outside your target area.
I always create a measured drawing, but if you assume at some Target distance T, the circle of illumination will be 1/2 T in diameter. Does your beer keg fill the entire FoV? (Photons NOT hitting your target are averaged in with the one that do.)
Sometimes one can brighten up your target with a bit of reflective tape. But if it's a real beer keg, that aluminum is already pretty bright.