You don't have to depressuize.
Two screws, and the fore arm comes off.
Loosen the set screws on the barrel band and slide that off.
Remove the 4 action screws (have to de-scope to get to them).
Lift the barreled action straight up (be careful not to lose the transfer port).
Set the bottom 1/2 the gun safely aside.
Unscrew the end cap of the shroud.
Unscrew the shroud body.
Remove the odd ported plastic piece from the end of the barrel (it just pulls off).
Undo the one set screw on the part the shroud screws into (there is an o-ring behind it, up against the breech...don't lose it.)
Loosen/remove the two set screws on top of the breech (that hold the barrel in place).
Pull the barrel out of the breech.
EVERYTHING goes back in reverse order with the new LW barrel....except for one TRICK;
the threaded part the shroud body screws onto has to go on to the new (fat in the middle) LW barrel from the breech end. With the standard Crosman barrel being one stright diameter, could side that piece on or off from either end, but because the LW barrel is fat in the middle, it has to go on from the breech end. Put that part on first.
A FEW PIXS:
Comes ready to go, o-ring in place. Can see how the LW barrel is fat in the middle, only machined at each end to the skinny Crosman diameter inorder to let the issue parts fit back on.
You will have to excuse the gold color from the artificial lighting...its really steel-silver.
LW barrel shank (machined for set screw placement):