Hardware store or a crafts hobby store sells long round wooden dowel sticks even Wal-Mart. Bring a 25 caliber pellet with you and be sure to buy one or 2 wooden dowel rods that are a hair smaller in diameter. Too thick won't fit inside your barrel so it's got to be a little smaller than the outside diameter of the pellet you bring with you. Too skinny it may break while attempting to ram the pellet out. They're cheap buy at least 2. You can even use them to clean inside your barrel easily with lubed patches instead of a pull through.
Possibly you double loads also you might have a leak. See if air, like buff, comes from the pellet prob or not while shooting, if yes then you have to adjust the prob to the right manufacture spacing and to remove the stuck pellets if any by rod or another shooting.
That sound effects is mostly a jam pellets, the air has no where to go but out the pellet probe and pressure still remain in between vs and pellet so if you open the cocking handle you will release the remaining trap air.