Difference between 4" m17 and m18? Is it the rib?

[AEM]

I've always been curious why S&W produced a 4" m17 K22 when they already had the 4" m18 .22lr Combat Masterpiece. I have a m18 and a 6" m17, so the different barrel length, rib and front sight are obvious differences.

But I've never seen a 4" m17 K22 up close so I don't know how it compares to the m18. IIRC, both have Baughman ramp front sights, so the only difference I can think of would be the width of the barrel rib. The m17 K22 6" I have has a wider rib than my m18.

 

[k22fan]

The defining characteristic of the 18 was its light weight barrel. Like the 6” and 8 3/8” 17s, the 4” 17’s barrel and rib have a slight straight taper resulting in a heavier barrel than the Combat Masterpiece’s. Just like 15s, the barrel diameter of 18s reduce fast just in front of the frame then taper more slowly for the rest of their length. Also the top front corners of Combat Masterpiece frames are scalloped in to mate with a skinny barrel rib. The last style of 4” 17s had full lug barrels with no taper at all the same as FL 4” 617s.

IMO, the 1985 change from 18s to 4” 17s cut manufacturing costs at the expense of the 18’s character.

 

[fyimo]

The Model 17 in 4 inch really didn't happen until 1986 on the 17-4 with the heavy barrel and then the 17-6 that came out with a 4 inch barrel and full under lug.

 

[AEM]

That clears it up. Thanks, guys!