no variations / easyThis no-block square method has been adequately explained in Puppy Love's Strategy Guide, but I will repeat it here to be thorough.
Accelerate toward the pill then decelerate so that your crosshairs rest between the middle and the edge nearest to you and start firing. The pill will shoot a single shot, which will hit you, and then send a solid line of bullets. You should take the first bullet and keep firing. Turn and accelerate away from the pill (hold down the accelerate and left or right turn buttons simultaneously) just as you are hit by the line of bullets. You should be able to do this and still have more than half of your armor left. Often there are buildings or trees you can run behind to absorb some of the shots from the pillbox.
Wait a short amount of time. How long you wait depends upon the minimum amount of armor you want to have when you are done. I usually wait about ten seconds, which leaves me with 2-4 shots of armor after the pill is dead.
Accelerate again toward the pill, rest your crosshairs on the side of the pill nearest you, and start firing. Your goal with this pass is to kill the pillbox. As soon as you have fired enough shots to kill it (it will be easier to tell how many with experience), run away again so that stray shots will not drain your armor.
LAG: The Hardliner Method can be unpredictable when your game is lagged. I would go as far as to recommend using a different method if the lag is particularly bad.