That's not too surprising. Of course, that might be a safety net. My max sync speed is 1/250, but line of sight I shoot at 1/320 with no problem using my skyports.
Gawd photographers of today are so spoiled...X sync of 1/250 today is common, and when I first started, 35mm focal plane cameras were limited to 1/60 and medium format focal plane cameras were 1/30. You felt great when a rare camera with the Copal metal blade focal plane shutter let you go up to 1/125 



