I'm new to DCS and the F-5E, but messing around last night I found what seems to be a relatively reliable way to hit things with Mk 82 Snakeyes, or at least a good starting point for more experimentation. Set the gunsight to Manual mode and set a depression of 100 mils. Set the snakes up for ripple, 0.10 seconds timing. Fly at 300 ft and 400 kts, and drop when the pipper is on the target. Remember to hold the pickle until all the bombs are gone.
That gives you enough speed and altitude for the snakes to deploy and not blow yourself up, but low enough that you should be pretty hard to hit with AAA. I haven't tested it very much yet, but with the center rack of 5 bombs I was able to take out single vehicles.
When fully loaded the F-5 should be able to do over 400 kts if you let it accelerate for a while in straight and level flight, so you may have to slow down near the target or pop out your speedbrakes for a bit, or figure out some other mil setting for the sight for higher speed. I have read that Snakeyes have a max drop speed of 450 kts (any faster and the drag fins may not deploy correctly), although I haven't tested that in the game.
