In Buried, purchase the LSAT off the wall and Pack-a-Punch it.
The LSAT is founded in the starting area. You will need to survive for two or three rounds to amass enough points to buy it. When you have enough, go to the broken staircase. Hug the left side of it and jump. Press to grab onto the ledge then quickly buy the LSAT on the wall. As soon as you do that the ground will break. From here, just go through the normal steps of Pack-a-Punching a weapon. You can keep it inside the wardrobe until you are ready to Pack-a-Punch it to avoid potentially losing it.
This video also contains a guide for Revisionist Historian.
When i first played i though "YES! ammo for the LSAT :) so cool" this is not true, you only have one shot at getting the LSAT... In the Beginning Room, if you go to the broken stairs and look up to the right, you'll see the LSAT on the wall for 2000pts Jump from the broken stairs to the platform and press A rapidly to climb up. BE CAREFUL! you only have one shot to get it because once you step onto that platform you only have about 5 seconds to grab it before the platform collapses and your chance is lost...
@ #26 yes you can even buy ammo in that way, or if the platform is already gone and you want to trade the paralyzer for the LSAT you can use it to fly up and as you slowly go down make sure you're right in front of it and looking at it while holding X
so anyone know why i cant put the FSIRT in the locker? I had one in it from the first game i PAPed a LSAT and i took it out and never got to put it back in, so i started up a solo game so i would have it in the weapon locker, saved up the points to buy it and to pack a punch now its saying i can't store it like it's a wonder weapon or something