I do get concerned with the numbers that are some time quoted for the chain stretch.
The SSM says the limit is 128.9mm (5.07") from center to center.
Now every machinist knows how to measure c2c without guessing where the center of the pin (or hole) maybe. And it's easy for them as they usually (at least now of days) have a digital caliper. With these wonderful measuring sticks to measure c2c place the jaws over one pin and reset it to zero. Then every measurement made will subtract one diameter. So if you measure from the outside of one pin to the outside of another, you automatically get the c2c measurement.
For those of you that don't have a digital, add the diameter of one pin to the requirement.
128.9mm(5.07") + 2.95mm(.116") = 131.85mm(5.191")
BTW no need to count the number of pins, just start with 5" and go to the next
longer pin. If that doesn't work then I sure do want to see your chain
as it's likely to be the most stretched chain ever seen.
And I think it's been said that a new chain is 5" long, so if you measure less than that, try again.