Some have asked me in the game about my 30mm shooting and even questioned it at times so I thought I'd give my insight on the Mk108 30mm.
The most general tip I can give is instead of visualizing lead [ ] this far in front of the bandit's flight path at a given range, visualize it [ ] this far. I think most players have a very natural feel for 50 caliber lead ranges. For the 30mm tater, you have to essentially double 50 cal lead at each distance i.e. 200 yards, the lead for the 30mm will be around the 400 yard lead for the 50 cal. If you connect with bbs and miss with taters, you most likely undershot. This is the most common way 109K4 pilots miss their shots. Get in the habit of trying to overshoot the bandit. It's incredibly difficult to overshoot with a tater and practicing this will train yourself to get the correct leads.
Here's a film of me forcing an overshoot on a fast plane that is nose down at me.
http://www.dasmuppets.com/public/Grizz/CrossingShot.ahf (Save target as)
I remember when I first learned how to do this, everything seemed to be happening so fast. You have to track the plane in your views as you roll around him and then somehow fire 30mms as he zips through your front canopy and hope you hit him. Here is essentially a play by play for what I try to do in each step of this overshoot maneuver. Watching the film first will help with the steps in these screenshots. (I apologize for the crappy graphics)
It is absolutely necessary to track him through your views the entire time. This is a picture of the bandit in my top view. The basic goal here is to force the bogey close to center and to fly out the bottom of this view. The red line shows his predicted flight path, and the green box shows my target area for where I want him to fly out of. As you can see I am pretty close here. I prefer for them to be slightly off center to the left and I will explain that in the next step.
Here's the next view he is tracked through. As he flies through the center bottom of your top view in the previous screenie, switch to your front top view and he will fly out of the top center of this view. Again, the goal here is to force him out of the bottom of this view and into your front view for gun solution. This is right before I begin to twist my plane to the left.
This is an important moment for twisting your plane preparing for gun solution. Rolling to the side is a very important step in setting yourself up for a gun solution with high visibility. You want the bogey to be sweeping through your front view Right to Left(my preference) or Left to Right. This is the best way to avoid having your view obstructed by the aircraft's frames. The 109K4 rolls best to the left and this is why I set up slightly off center as I set up for the shot. I like to be off centered slightly because when I twist into gun solution I like to have a little buffer zone for where I can use slight Positive G elevator to make last second adjustments if he alters course. If you are dead on and he alters his flight path going underneath your nose, you have to push negative G to get gun solution back on him and this is not a very accurate situation to be in. Essentially it gives you a little bit more room for error.
As the bogey begins to come into your front view, I like to 'wait' on the horizon as I finish twisting into position. I try to set up my sitting position far ahead on his flight path (the red line). You almost want to get your nose as far out in front as you can, line it up, and 'wait' for him to fly into 100-200yd gun solution.
This is a few milliseconds after I have fired 2 taters at him. The blue box represents the lead area you want to be in at this range (~150-200yds). The reason I extend the box quite a ways in front is because you can never lead too much! It's better to over lead, and spray 7-8 taters and let him fly through them, than under lead and hit with 4 bbs and miss with taters. If you aren't lined up perfectly on the center of his aircraft, there is some luck involved in hitting a wing. Taters sometimes have a nasty habit of missing above and behind wings, in the bends of the aircraft.
And a sweet kill shot for the reward.
Any questions children?