Inconsistent FC test results

[Unckle Brewski]

I'm having trouble getting consistent chlorine results.
I'm in the SLAM process.
In 4 consecutive tests this am these are the results:
20.5
15.5
14.5
22.0 (5ml sample)
All tests were using the same "master sample" within minutes of each other.
All test supplies are current....not old or outdated
The only thing I can figure is the amount of powder used??? however I try to be consistent within reason.
I'm confused
FC: see above
CC: .7
Ph: 7.5
TA: 110
CH: 425
CYA: 55
Salt: 3400
Temp: 84
With the exception of chlorine these test results were prior to start of slam.

 

[mknauss]

Biggest variation is normally droplet size of the R0871. When you get to high FC levels, the number of drops needed starts to exacerbate the error.
Be sure the R0871 reagent bottle is vertical. No pressure is used on the bottle to force droplets out. Let them form and drop off. Using your Speedstir is paramount.