Nazi Reichstag

You destroy all the aa bateries and kill the germans on the stairs then a russain guy runs up and moves the sandbags out the way so you can enter
Though what happened with me once was the guy didnt clear the bags so I was stuck and I had to kill myself and do it again

You have to finish the objective of destroying all of the AA batteries before you can get into Reichstag. Once you do that, you have to kiil enough Germans on the steps of the building before you can get in.

Once you have destroyed the 4th and final AA gun do this. SHoot the german down the side of the building to the far right then sprint for the side of the building. You may need to shoot the German in the top window of this building before you start and throwing a grenade in the front door will also keep their heads down as well. Once down the right you can kill all the germans in the building through the side windows. Go back and enter the building from the front where you threw the frag. Now clear any germans shooting from the building next door. Once done there go upstairs. Be quick, there are 3 Germans there. If you struggle here, head back to where you started and shoot them from outside. You should be able to get the German in the top window from the bottom of the ladder inside the building. When clear, go up the ladder and you will find a sniper rifle at the far end of the floor. SNipe the germans on the Reichstag steps and in the 2nd floor of the Reichstag. This should be enough to let your men advance into the Reichstag.