Air Venturi Air Venturi suppressor trouble

Hello my Avenger end cap unscrews. If it is an Avenger X I do not have one yet so can not answer that.
I have a regular avenger it the X. That's what I thought, I tried unscrewing the end cap with some pliers because I couldn't by hand but no luck. I couldn't unclscrew even with pliers and managed to scratch off paint.

Will give it another try after work later tonight ...

Thanks for the reply Sir