i can't find anything more than what's on jogunn's site about tuning, no mention of altering the length at all for different frequencies,
what is good for 26mhz is good for 29.5mhz with a tweak of the gamma according to the instructions,
i have see one guy claim his gunn is 28ft,
the way i see it is its very likely 24ft+ of radiator which is a long 5/8wave @29mhz,
the only way to know the length for sure is measure one that has not been messed with, then maybe model it on 29.5 and 26mhz,
gamma fed scaffold poles about 3/4wave work but not nearly as good as a similar length sigma4 in the same mounting position,
everything i have read says that going longer than .64-5/8wave causes high angle lobes to form at the expense of low angle radiation, your 26ft model looks to be inline with what i have read,
i don't think there were any secrets in the base, if you read his later description its tripple walled tube, everything grounded like a sigma4 with the radials folded down,
we don't know how your buddy has his gunn set up, also take into account you don't see much difference between any two antennas in your area like some of us do,
jogunn antennas look pretty well made, 6063-t6, not the best tube ever used in cb antennas as they claim, not even the second best but it looks and feels heavy duty compared to the vector 4000 tubing,
several locals have bought vectors then bailed out when they assembled them and realized what 30ft of flacid aluminum looks & feels like.
