Im aware this is an old thread but I recently had this happen with the EXACT charging handle (FFT 3/4) during firing and thought this was interesting.
I was shooting standard buckshot and after the bolt locked back on the final round I noticed the charging handle was missing. I found it after 5 minutes of scrambling on the ground but made me reconsider going back to the OEM handle.
Nice, I am definitely a Benelli fan boy this is one out of all the firearms I own I would never sell. My M4 is nothing crazy, I tried to keep it as stock from the factory possible other than a FFT trigger upgrade and a little stippling on the fore end.