What are acceptable Chrono results?

[AtownBcat]

I was doing a little load development and settled on a load that shot very well in my 300WM. The load is as follows:
RWS Brass
76.5g Retumbo
CCI Mag primers
208 A-Max
This is an accurate round. I have shot several 5 round groups between .259(almost able to call it a .25....)and .313.
I decided to shoot 2 ten round strings to get some velocity data.
My first string was with sunshine overhead and the second string was with the sun dropping down behind a wall so there was not direct sunlight.
The chrono is a CED M2. The unit was 15ft from the muzzle.
First 10 rounds
2894(cold bore)
2908
2925(this round the bolt was a little hard to close the bolt, wish I had replaced this round with another one)
2900
2892
2898
2909
2902
2888
2890
so the Average was 2900
ES was 37(that one round jacked this up)
and a SD of 10.5

The second string was a little crazy...
2913
2919
2868
2914
2900
2856
2886
2844
2848
average 2875
ES 110
SD 34.9
Im tempted to throw the second group out but it still messes with my head..
What are acceptable ES and SD numbers? Should I be using the light packs to get more reliable results? What are your thoughts about my results?

 

[Hookturnr]

Definitely some issues there..I would look at the second set with a questioning eye. Did you notice any change in group sizes while shooting these strings? What range were you shooting at? Was the rifle shot hot/cold? Too many variables here before you even get into the lighting for the chrony. I would most likely shoot another 20 with a consistent chrony setup and target at 300yds min. to correlate my velocity readings against. After that, then you will have a better position to decide what to do with that first batch of results.

 

[grit]

I like to shade the chrono and use artificial light. I'm always after single digits.