1) I'd recommend going STT on a contact within about 8-10 miles, use auto acquisition as needed if you're tally...Remember that the cone shortens at closer range, so proper cursor AND altitude bracket placement is critical here - You don't have much time in that scenario, mistakes will spell quick death (against something that isn't an AI, the AI is forgiving of your mistakes.). BTW, if you're up high, get your head outside of the cockpit and try to find contrails...You won't miss them!
2) Check your controls, you might have some sort of binding issue, I can hold the trigger down (using a TM Warthog) and spew all 940 rounds real fast. That said, NOT holding the trigger down is nice sometimes...Accuracy, yo!