When the Model 18 was discontinued in 1985. Any subsequent 4" .22s were called 17s or 617s if stainless with different dash numbers.

17-4 was a 4" heavy barrel with no heavy lug,
17-6 was 4" w/full lug,
617 had the full lug 4"
and there was an "exclusive" 617 made only for Ashland Shooting Supply.

None of these 4" models were made for very long.

Most Models do not have a different model # because of a different barrel length. Another was the Model 34 22/32 Kit Gun in 2" and 4". But in 6" it became the Model 35. Go figure!

__________________
Jim
S&WCA #819