Ok, just had a fantastic blonde moment. 
Now I know that the existing 'Recharge Time' ALWAYS produces a result of 7 secs, so I said to myself what if I just include a -1 somewhere in the formula, soooooo......
Recharge Time = RoundUp((16 x AttackSpeed) - (FlingShotSkill / 100) - 1)
I pondered how I was going to test this then I remembered someone mentioning the cap time you currently have is displayed when you keep hammering the special, e.g.:
You hit OT Bartender for 625 points of Fling Shot damage.
Unable to perform action, Fling Shot skill is locked, able in 00:00:43
Unable to perform action, Fling Shot skill is locked, able in 00:00:43
Unable to perform action, Fling Shot skill is locked, able in 00:00:43
I tried the following weps and used the existing 'Skill To Cap' and the slightly altered 'Recharge Time' formulae:
Code:
QL122 Balanced Oneida Razor Half-Bow
AttackSpeed: 2.55
Skill To Cap: 3380
MyFlingShotSkill: 1226
Recharge Time: 28.00
You hit OT Bartender for 1557 points of Fling Shot damage.
Attacked by OT Bartender!
Wait for your previous special attack to complete.
Wait for your previous special attack to complete.
Unable to perform action, Fling Shot skill is locked, able in 00:00:28
OT Bartender: Get lost while you still can, Levinstein! You're next!
Unable to perform action, Fling Shot skill is locked, able in 00:00:28
QL23 Cast-Off Blackhole Mk IX
AttackSpeed: 3.50
Skill To Cap: 4900
MyFlingShotSkill: 1226
Recharge Time: 43.00
You hit OT Bartender for 622 points of Fling Shot damage.
You hit OT Bartender with nanobots for 1272 points of projectile damage.
Wait for your previous special attack to complete.
OT Bartender: You will pay with your life for that, Levinstein!
Unable to perform action, Fling Shot skill is locked, able in 00:00:43
Attacked by OT Bartender!
Wait for your previous special attack to complete.
Unable to perform action, Fling Shot skill is locked, able in 00:00:43
Sooo, what can we summize from all my faffing?
• The existing 'Skill To Cap' formula is correct.
• That there was an anomily in the 'Recharge Time' formula. 
• Fling Shot has a FIXED cap of 6 secs and anyone/anything that mentions 'cap + attack' is infact incorrect.
Well, there we have it, a -1 fixed the problem. 
Althought this was a slight anti-climax and I wish the formulae I'd made in the previous post where correct at least we now have a more correct formula and tested it. 
Guess my work here is done...I'll slink off elsewhere now.