I bought an F1 Chrony and got a cable from a bloke ("stot" on airgunbbs.com) who was making them, to link the F1 to my Laptop so I get live feed in CSV which will convert easily into Excel files, so I can generate lots of pretty graphs showing how fast my rounds go.
I can analyse the extreme spread to my hearts content now.
It is very useful actually.
Based on the data from the Vit web site, I had been using 46Gr Vit 160 on 87Gr Hornady Vmax which gave 3224FPS.
I downloaded to 44Gr to get 3090FPS.
Only thing to watch for with the F1 is sunshine, I have a large piece of white card to stick to the diffusers in case the sun is not directly overhead and shade cast by the diffusers do not shade the sensors.
£5 for a tripod on the bay.