Am I right in thinking that if you play as Grey company on SBG there is no bow limit?
Or do the new rules suggest it can still only be a third?

The reason I ask this is in the Ruin of Arnor book it has the following.....
ARMY SPECIAL RULE
In Legions of Middle Earth games, the Grey Co. is not restricted by bow limit. You may instead include upto four Rangers of Arnor for each Dunedain or Ranger of the North in the same force. For example, an army thatincludes 4 Rangers of the North and 1 Dunedain could also field up to 20 Rangers of Arnor.


Please advise

You can use the rule you have just quoted.

No bow limit, but, as it suggests, a dunedain/RotN for each 4 rangers. These are Independed heroes (can't have followers), so you'll still need another arnor hero for each 12 rangers you take.

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Ours is the fury!

Bonus

But how would it work with a mixed force for example as above but also with ellahan and elrohir and if I wanted to take some elves with those two has my bow limit been taken up by the rangers or do younot include them in your overall number when working out a third of your force?

Each ally has their own bow limit. So you can have 100% bows with GC (provided you have the appropriate heroes to lead your warbands, plus enough RotN to cover your 1:4 ratio with RoA); and your elves can still have 33%.

Thanking you kindly.......