so you are saying if the band i want is stiff i should go for 22mm?I have the 42mm Black Classic buckle from Apple and put on a strap that is marked as 24mm but measures closer to 23mm. Here's a photo. I think you could squeeze on a true 24mm strap, but it could be pretty tight if the strap is bulky and/or stiff.
I wish I could answer for sure but the 22mm Nato strap I ordered disappeared somewhere in USPS. Scheduled for delivery May 22, left a regional facility, and then POOF! Gone. A 24mm might be okay but order from a source who will exchange or refund and you're set.