Wouldn’t the opposite happen and the shrink wrap expand?

I had an 18650 get stuck in a first generation DQG 18650 mini once. This was the original twisty version of the light. The tube tapered as you got closer to the spring. If you stuck a fat cell in it would fall in and then get stuck.

I only managed to get it out when I drilled a tiny hole in the bottom of the tube and inserted a large paperclip to push the cell out. I don’t recommend this strategy unless you’re really frustrated as it caused permanent damage to the light including destroying the waterproofing.