Go buy a surplus 26.5MM flare gun, and some illumination rounds. Go shoot them.
Imagine an Estes model rocket, chock full of fusee compound. THAT kind of rocket. Not a F*CKING V2!
Anyhow, there are 40MM grenades capable of penetrating quite a bit of armor, provided they hit correctly. ALL light anti armor munitions depend on a Munroe effect explosive charge, and if this is not square to the armor, the jet will do weird things.
If you want to take on a tank like the M1A2, I reccomend approaching it from the rear quarters (NOT DIRECTLY AFT, as the rather warm gas turbine poots out there) and get ON the vehicle. Using a ball pein hammer, proceed to break EVERY vision port, viewer or generally valuable looking item attached to said vehicle. When the crew realizes you do not have anythig BUT a ball pein hammer, they MAY try to come out, and cause YOU considerable bodily injury. Smack their fingers sharply with the hammer as they attempt to exit.
Eventually, the TC will become annoyed profusely. You will experience the massive accecelleration the M1A2 is capable of, followed by a demonstration of it's stopping ability. You will probably end up in front of the vehicle in question. Moving now would be wise, but your next (and last) visions will probably be a close up of a track block.
Any other questions?