Ok a few quick questions.
What gun are you using?
What EXACT size pellets are you using?
There are more than 5.5 there are 5.52 5.53 etc etc but most tins merely put 5.5 on the tin when in fact it could be a lot bigger cal
Which end of the gun are you trying to clear the blockage from.
Remember there is choke on some rifles at the front of the barrel so the further toward the front of the rifle the tighter it will get.
Try a ram rod from the forend and push the pellet back toward the breach with a little pressure it SHOULD clear.
With the S-16 there was a tendancy for people to cycle shots (without closing the breech propperly) thus the air was not enough to get the pellet out and when cycle a second and third shot they simply jammed the barrel.
I find a flat ended rod with either slight pressure of a tap from a rubber mallet will clear most blockages but ALWAYS from the muzzle end pushing the pellet back out of the breach
Zeb
It sounds like you have a tight barrel and need the smallest cal there is going.