We used stressproof for cylinder pins and pins for other moving joints on our off highway trucks (mostly 1.5 and 2" TG&P) until it became too expensive to get the LaSalle product. The standard substitution is cold drawn 1144 - not 1144L, which is the free machining version with lesser mechanical properties. 110ksi tensile, and acts softer than the numbers would indicate. It does induction harden nicely leaving a thick hard surface and a tough core, at least on larger diameters. It would not be my first choice for your application as you describe it, or as I understand it. 4140 has better mechanical properties, harder surface, and better fatigue properties. On the other hand, a .17 isn't going to beat the action up like a 30 cal would. One other consideration I just thought of is that the surface property enhancements of cold finished rounds are, well, at the surface. Material should be close to final size or you take the chance of cutting off the good stuff - may not be a big deal getting to 0.211 from 0.250, but would be starting from 0.375.
Sounds like a fun project.