I measured this the same way I measured the girth of the grips. I.e. I placed the tape measure all the way around the grip and around the trigger. I figure this gives a measurement more like the hand gripping the gun.
The Sig 229 measured 7.5" and the Glock 7-3/8". Remember that's a girth measurement - around the grip and trigger.
Hmmm, wait a minute, those measurements can't be right because they're the same as the grip girth measurements. I bet they are 8.5" and 8-3/8" instead. Shoot! I'll have to re-measure that tonight.