Measuring MV

[Miseryguts]

Hi, bought myself a Labradar for Xmas, and having some difficulty understanding how it measures MV. I get the measurements down range and the science behind it, but how does it measure MV when the unit is anything up to 18 inches from the side of the muzzle and level with said muzzle. Surely the first measurement is when the bullet first breaks the beam, which can be several feet from the muzzle - so is that what it calls MV, or does it extrapolate back to the muzzle?

Enquiring minds need to know

M scratching his head in sunny(for once) Monmouthshire

[Roy W]

You should be holding the barrel alongside the unit, not sure why you would hold it 18 inches away?

The radar isn't a 'beam' as such, it is a continuous 'wave' 

If you hold the barrel next to the unit as per the instructions the MV will be near as dammit at the muzzle.

 

[Re-Pete]

When I first used mine, I tried it simultaneously with a Magnetospeed, and with the muzzle positioned as recommended, the results were within 10fps of each other.

Pete

[Miseryguts]

2 hours ago, Roy W said:

You should be holding the barrel alongside the unit, not sure why you would hold it 18 inches away?

The radar isn't a 'beam' as such, it is a continuous 'wave' 

If you hold the barrel next to the unit as per the instructions the MV will be near as dammit at the muzzle.

 

Hi Roy, yes I do put it close to the muzzle, one of the unit settings is distance from muzzle - these are 0-6, 6-12, and 12-18. I use the 0-6 setting.

So, you say that the output is not a beam, but a wave spreading in all directions like the ripples from a stone dropped in a pond? If that is correct, then I can see straight away that it will measure true MV. Obviously I had the wrong idea of the science - Thanks for the clarification!

M snoozin' in Monmouthshire