10/5/20:

Run 1: 

Pressure: 27.5 PSI , Launcher Angle: 70 degrees, Payload: 2 canisters with candy Weight: 52 grams

Horizontal Distance: ~45'

Vertical Distance ~45'' estimated.

Conclusion: Good

Run 2: 

Pressure: 27.5 PSI , Launcher Angle: 60 degrees, Payload: 2 canisters with candy Weight: 52 grams

Horizontal Distance: ~45'

Vertical Distance ~45'' estimated.

Conclusion: Very similar to Run 1 at 70 degree.

10/4/20: 

Ruled out shooting candy without some kind of a container. Considered using plastic Easter eggs since several were available. However, no PVC tube is made with 1.75" inside diameter. Only 1.5" and 2.0" are available. 35mm film canisters were also available and fit nicely into a 1.5" PVC pipe.

Purchased the PVC parts to convert the 3/4" Female thread on the sprinkler valve to 1.5" PVC tube that would fit the film canisters.

Assembled the systems and ran several tests

Run 1: 

Pressure: 40 PSI , Launcher Angle: 80 degrees, Payload: 1 canister with candy Weight: 26 grams

Horizontal Distance: ~47'

Vertical Distance ~60' estimated, possibly higher.

Conclusion: Way too high

Run 2: 

Pressure: 40 PSI , Launcher Angle: 80 degrees, Payload: 2 canisters with candy Weight: 52 grams

Horizontal Distance: ~40'

Vertical Distance ~60' estimated, possibly higher.

Conclusion: Way too high

Run 3: 

Pressure: 35 PSI , Launcher Angle: 75 degrees, Payload: 2 canisters with candy Weight: 52 grams

Horizontal Distance: ~60'

Vertical Distance ~60' estimated, possibly higher.

Conclusion: Way too high

Also tested:

Plastic streamer taped to the canister to slow decent. Worked well but reduced distance to ~35'. 

Parachute from a napkin also taped to canister. Worked well but reduced height and distance. Only traveled 13'. Opened on the way up.