There are two different 219 designs now. That is why you are seeing what you are
Not my words
There are different versions of Savage 219/220 single shots, and all barrels are NOT interchangeable.
There are Model 219's, 219B's 219C's & 219L's.
The Model 220 has a similar, but non-identical progression of improved models.
The earliest 219's & 220's were striker-fired, and were re-cocked by the opening action of the top lever, which incidentally released the barrel lock so the barrel could be swung open, and the shell ejector tripped off.
Any early or later 219/219B/219C/219L/220 rifle or shotgun barrel will fit and operate just fine in the early 219/220 guns.
Then, Savage changed the internal design, from a striker to a concealed hammer - which the operation of the top lever no longer was able to re-cock.
Soooo, on all subsequent models, there is a cocking lever inside the front of the action body, which lies alongside the barrel's locking lug when the gun is closed, or in the firing position.
The cocking lever/arm is raised, re-cocking the gun, only when the barrel is swung open (not by the top lever opening) - by a spring-loaded stud located in the side of the later model's barrel's locking lug(s).
These guns are the 219B/219C/219L, and later 220's.
These later guns ergo require also a later barrel, WITH the cocking lug - which is absent on earlier barrels.
The early, no-cocking lug barrels will not re-cock the later guns - burdensome, to say the least.
The easiest way to check YOUR gun, is to remove the barrel and peek inside the right side action wall, to see if it has a cocking lever there.
If it has one, the gun needs a barrel with a cocking stud.
If it has none, the gun can use any barrel.
Within the barrel interchange limits, defined above, any 219 or 220 in good/serviceable condition is safe with any other 219 or 220 barrel in good/serviceable condition.