You might get away with it, but I sure wouldn't recommend trying. The risks just seem too high.
Instead try either blowing air into the cylinder with a small tube (to leave room for the shell to come out), or sucking it out with a vacuum connected to a small hose. You may have better luck if you turn the engine over by hand to bring the piston up near the bottom of the intake port.
If both of those techniques fail, the next thing I'd try is getting a small USB borescope and using it to find the shell and then decide how to go after it. You may want to look for a borescope with a bendable "gooseneck" for the last few inches so that you can have some control over where it points. USB borescopes are relatively inexpensive (far less than what it will cost you to pull a head) and you'll probably find lots of uses for it.
If all else fails, pull the head – or try running it if you're the gambling type.