Thanks to this video guide I was able to do all maps of last stand on realistic solo. Thanks to Tyger7 at x360a for creating these videos. http://www.xbox360achievements.org/forum/showthread.php?p=30...
1. I did like the guide instructs and used all gadget upgrades on uniform. It worked well when not getting shot.
2. A few levels required a few tries to for me to find the proper position or where the enemy saw and killed me because of stupid mistakes I made.
3. Don't worry about the emp. Even if it gets below 25. When you die and retry it will be back at 100.
4. You only have to do waves 15-20 for this achievement.