Have a look at this Scott C13 (N.S.S.C. AM14)
Unitrade identifies this Labrador Issue " Put to flight" stamp as either
14.3 x 14.3 and
13.8 x 13.8N.S.S.C. identifies perfs as
14.3 x 14.3 and
13.8 x 13.8.
See stamp below...

This is the perf taken at 13.8 x 13.8 as per Unitrade and N.S.S.C.

This is the perf taken at 14.3 x 14.3 as per Unitrade and N.S.S.C.
This is my stamp 14.0 x 13.8
What do you think..Maybe a possible perforation needed..??Robert