Carry distance gc2 and tgc

[Captargo]

Curiosity question
when using mthunts driving range, most of the time the carry distance displayed by Tgc and on the gc2 is the same or very close
when I use my 7 iron however, I have sometimes had differences as high as 8-10 yards, Tgc being the lower amount.
does that make sense?

[mthunt]

A lot of variables effect carry. The GC2 doesn't account for elevation. Down the middle on that range has no elevation. The GC2 firmware, GSX version and TGC version can effect carry as well. Lastly spin. The GC2 uses a different algorithm for spin then TGC. The GC2 really really loves low spin. If back spin is low the gc2 will give you more carry than TGC. The tour average for spin is 7000. It would be similar for a low handicapper. If your spin is lower than 5000 IMO the GC2 will show more carry.

[Captargo]

Cool, thanks
I will look more closely at the spin rate next time this happens.
guessing spin rate might be the issue since all clubs were same or close and only noticed larger difference with 7 iron but it wasn't all 7 iron shots.
Typical spin rate for my 7 iron is around 6k but sometimes I see a much lower spin rate