Yes, Shvak have an incredible dispersion, laterally and horizontally. Your best bet is to keep your convergence below 300 yds and walk your tracers into a target with snap shots.
Also, my personal advice: SHvak drop quite a bit, so best method by far is to avoid high G deflection shots like the plague. Until you get a few tricks on how to do them keep your oppenents moving until you can get the 6 shot you want. In fact, your SHvak have such low muzzle velocity I wouldn't reccomend much deflection shot at all.
Scissors: Easily done, remember to keep changing position and pulling. Sustained turns bleed E well, play the piccilo with your throttle to keep flying level while slowing down. DON'T do this against a Nik1 or Spitfire. Both will pick you apart easily and laugh at you. Don't reccomend against P51 either, until full FM comes out they are not suffering low speed stall much and can still hang on and pick you off.
And a final note I learned from Leonid, that can easily apply to all. Learn how to dogfight when your starting. Fly the plane with flaps down a notch, manage throttle, scissor, turnfight and learn the tricks to setup low G deflection shots.
Then always grab altitude, fight vertical and never use it unless you NEED to!
------------------
If your in range, so is the enemy.