Gamo Gamo arrow shooting

My son Gamo arrow sounds and shoot like a springer, like I said before it have a little kick like a springer and it louder than the one on YouTube. All the videos arrow seems to be death silent, the one we have got a pop sound to it.
Mine is dead quiet too. Accuracy is very acceptable. The shot string is pretty consistent through the first 40 shots. You may have something going on. If you care to, I would push the two roll pins out of the integrated moderator, remove the moderator end cap, pull the red air stripper, use an allen key or some sort of hooked scribe to insert into the stripper and tug it out, make sure all is seated correctly and not damaged. The air stripper should be contacting the front of the barrel but not out of place impeding the bore. There is a ring on the end of the bore side of the air stripper that the barrel seats into. Hope you get it working proper because it should be accurate at 50yds with a good clean barrel and whisper quiet. The only sound you should hear is the hammer striking the valve and the pellets impact after pulling the trigger. The hammer strike will make a slight popping sound, but it isn't obnoxious or anything. Mine shoots Crosman 14.3g hollow points like a champ and is very, very quiet.
 
Someone mentioned knocking the moderator pins out and looking for signs of clipping, or if it's not seated right, that's a good idea. It's easy to do that, I have punch pins but a brad or finishing nail would do, I had to remove the moderator, because I used some wadded up paper towels soaked in oil to shoot through and clean the barrel, didn't realize the shreds would get stuck in there, oops.