Well I finally got my 21Ks fixed and tested them earlier today. The first one shot around 50ft with the normal nozzle; didn't bother to measure that.
Then I tested the 2nd one which has homemade nozzles. On 3/16" the effective range was 54.3ft, and 60.8ft to the last drop. That was with only 8 pumps, as I was unsure of the strength of the current check valve seal.
Obviously, I am going to test it again today with different nozzles between 3/16" and 9/32". I am also going to add some more pvc cement to the check valve so I can get in a few more pumps without worrying about that area.
The best range I've ever gotten was 65ft on 1/4" with 11 pumps. 60.8ft on 3/16" with 8 pumps was pretty good, but I know I can do better! B)