Using a pencil sharpener, knock off the rear end. You don't have to make a real sharp point, just remove some of the excess dowel.
On the left, the edge to be removed was marked with a pencil.
Make small chip cuts smoothing out the curve.
Wrap some 220 grit around the dowel and turn it against the sandpaper like a slow moving lathe.
After that, sand up and down as shown in the inset picture.
Here's the new shaped tank next to the F-16 tank. Both look fine but the new shape is better and more streamlined.