How do you measure ping iron lengths?

[bangaio]

So... I have a set of ping g10s that I have been struggling to get with and of course it is all in the mind mainly because the 7 iron is almost the same length as the 8 iron, the gap between the 7 and 6 is bigger than the other irons. I have had a go at measuring from the end of the grip and the 7 iron seems to be around 36.75" which is the right spec and all the others seem to be 1/4" longer than spec - only I am not sure I am measuring them right, are the others all right and the 7 shorter than standard?
They all have the same serial numbers but a couple have been re shafted - still regular AWT shafts but some have black labeling on them which I think the i15 shafts might have had. I can hit them just fine most of the time - they're g10s after all but this odd gap in shaft length plays on my mind. Any excuse right!

So does anyone have any idea how to measure the length of a ping iron accurately short of taking them to Gainsborough. Where do I read my measurement from?

 

[macca64]

have a look on their website, look at the measurements, and see where they match on your clubs,

 

[bangaio]

But I don't know where to actually measure them - tape measure at the end of the grip but where do I read from? Where the club grounds? Where the heel starts to bend (almost the same thing)?