I don't believe that's correct. The ejector rod on my 2.5" M19 protrudes 0.82" from the crane. The ejector rod on my 3" M65 protrudes 1.33".
By providing lockup on the front of the cylinder with a ball detent on the crane for the new M66s, they seem to have a full-length ejector rod on the 2.75" guns. Mine is back at the mothership, or I'd measure it.