How to use subdivide on this shape that i cant name I'm kinda new to blender and i'm trying to model ww2 gun m1928 thompson.
Ive modeled a handguard at front of the gun:

When i try to apply subdivide modifier, it makes this weird shape:

Here is also edit mode of the object:

Ive used boolean value to create this shape.
Choose edges you want to keep sharp then go Edge&gt;mark crease (Shift+E) and drag up for maximum value