You'll probably get a pretty wide response, I haven't flown birds with wing mounted .50's in awhile. If I remember correctly I think I set the guns around 300. The best answer I can give you is to try different settings and see what works best for you. The ballistics will be the same on most the US birds but how you fly them may dictate a different convergence. I remember when I switched from the 51 to the F6F I brought the convergence in because I noticed that I was mixing it up it up a lot more than before so I set the guns to try and optimize the damage on a close in snap shot, like during rolling scissors. Try paying attention to the ranges your firing at and where you're getting hits at, then set the convergence there.