Q. Does your gun barrel leak water or gas? Or does your gun barrel heat up fast?
A. 99.9% of the time this is due to the barrel not being seated correctly.
Open the plastic door exposing the drive and idler rolls; this is where you should look for proper seating. The copper seat of the barrel should be flush with the aluminum block directly in front of the drive rolls.
If the barrel does not seat all the way down, the o-rings may need lubrication or may be damaged. But yes, it is possible to tighten the taper lock nut without wholly seating the barrel.
However, not seating the barrel all the way down causes greater problems. The barrel shaft and gun body inside dimension (ID) have a matching taper, if they don’t meet correctly, then the electrical path of welding power is not properly made and the ensuing misalignment causes the barrel to heat up within seconds or inches of welding.
But yes, it is possible to tighten the taper lock nut without wholly seating the barrel. Reference the photo of correct and incorrect barrel seating.
Our Prince® XL and Python® owners manuals state,
"... push the barrel assembly into the gun body until it clicks to a stop. To assure proper seating of the barrel, open the drive/idler roll door in the top of the handle. The rear face of the barrel should now be flush with the gun body."
The manuals go on to say, "Take care not to damage the o-rings when inserting into the body. Tighten taper lock nut assembly firmly by hand so that barrel cannot rotate while welding."
Correct and incorrect barrel seating ... push the barrel assembly into the gun body until it clicks to a stop.