a character-driven WWII movie from the 80s or 90s that I only remember one scene…

I think it takes place in England (maybe France??) and focuses on city kids during a bombing. This is the scene:

The kids are playing and scavenging thru the rubble, and they find a bombed out workshop and some loose ammo. One kid puts a love shell in a vise, hits the back with a nail and hammer, and almost kills another kid. I can’t remember if they run away or do it again.

Anyone remember that?