How many fps to add....

[Mush]

I chronoed some loads today.
The Shooting Chrony was in front of the muzzle about 15 feet (the lenght of the cord, yeah it is a beta one).
I got 2680 fps. How many fps would you add to get real MV.
I have read 5% thats 137 fps and I think it is too much.
Any ideas ?

 

[marcoman]

Isnipe shows difference of 13fps between MV and the 10m mark for my 300gr. SMK load (2760fps).

 

[swissinn]

Why not just put the chrony right in front of the muzzle? or like 2-3 feet away?

 

[Mush]

Why not just put the chrony right in front of the muzzle? or like 2-3 feet away?

Because the 338 lm shooting 300 SMK muzzle blast prevent any reading.

It could surely propel the chrony on the moon through space if it doesn't start to orbit half way.

 

[dero338]

Just put in your ballistics calculator the distance to the chrony

 

[Mush]

Just put in your ballistics calculator the distance to the chrony

You don't happen to use Shooter or Aplied Ballistic (both sre basicly the same) because I don't know how to do that.

 

[marcoman]

Just call it 2690 and be done. There will be variables during the days you shoot that will have wsy more influence on velocity and uour dope than being out on your MV by a few fps+/-.

 

[dero338]

i use JBM to put in the distance to the chorony and then I put the real muzle velocity in applied ballistic but to be honest it is probably a total waiste of time