When using rapid-fire weapons, people with full controls will often begin firing before they've quite lined up the shot and then sweep across the target, rather than try to perfectly aim the way Gauss and Rail users do. This also helps compensate for differences in the target's actual motion vs. the predictions of the lead-off indicator. Plus there's the simple fact that space ships are 3D objects, not points, so if your weapon has a tight auto-aim radius, you might actually be able to hit it even though you're not aimed close enough to the center of mass for the auto-aim snap and the auto-fire activation.

So, how to adjust auto-fire so that touch players can use this technique as well?

Add a setting for the auto-aim that allows the user to define how close they need to be to the auto-aim snap before the auto-fire kicks in. Auto-fire would still fire wherever the weapon is pointing, just as if the user had pressed the trigger manually, and any artificial delay to simulate reaction times would still be used (whether there should be such a delay at all is a different thread).

Additionally, this feature needs to disable itself when a weapon's refire delay is too high for this technique to be useful (e.g. with Gauss Cannon), I suggest making that number user-defined as well, so that people can tune it to fit their particular preferences (somebody who tends to spin faster might want a wider threshold, for example, while somebody who is very picky about when their weapons are firing might want a tight threshold).