E-Target SDs Question

[MikeMcCasland]

Gents,

I attended a match today that used E-Targets, and afterwards got to thinking.... would you expect to see more/less/same variation on the e-target SDs vs. what you'd see on your standard chronograph?

I was shooting a .223 with 90s, where I clocked 7 of them yesterday (magnetospeed) with an SD of 9.3. Today the ShotMarker was showing a SD of 19.1 for the 22rd string.

I'm guessing SDs inherently go up, because you're adding shifting winds into the equation, but wanted to see what others had experienced.

Thanks in advance!

 

[JohnKielly]

Several variables are likely to be involved:

• A seven shot string is not particularly statistically accurate; 22 shots are likely to give a better result.
• I suspect that you chronographed close to the muzzle. When you get downrange other issues become involved - the bullet to bullet consistency, relative ambient conditions you fired each shot in for example
• The open chamber E Targets do not judge velocity as time of flight between sensors that are a meaningful distance apart as most chronographs do.

 

[watercam]

Having shot many rounds over Shotmarker systems we concluded that velocity and SD numbers were not really accurate compared with good chronographs. Fairly close but don't take the numbers to the bank.