chinese midget (cube) chrony

. hey , yall , i'm noticing much slower reads when i shoot with the muzzle about one inch from the plane or first sensor…..when i scoot the muzzle back to around 8" my soft-tuned .177 gamo shadow 1000 goes from 152 m/s up to 262 m/s…… have you guys found an optimal distance away from the midget box to get your most accurate readings ? i know 6" up and 6" out usually does best with my (outdoor only) green f1 chrony , and about 12" back for co2 guns because the gas cloud throws it off……………but how far back have you found to be most accurate of speed testing non- co2 guns - when using these little $30 chinese chronys ?
 
I would think this is normal. Thinking about acceleration here. You are basically getting a lower initial reading when your muzzle is closer to the chrony and higher when you are farther away. Pellet is still accelerating out the barrel and down range till it reaches max fps and then starts slowing down. As long as you are getting somewhat of a consistent variation of FPS, then it should be correct.