I have always had a great respect for Silvertip ammunition. (I do understand in the scheme of things it is an old design)but when the Seecamp company had all sorts of issues with Winchester, I turned to all Gold Dots. I do have some older 9mm and .380 in Silvertips I use.I trust those.
Doug, I'd like to thing this is a case of lousy ammunition.
Go back to Gold Dots, check the function of the R9 with them. If you have zero issues as you had in the past, stick with the GD's. Use up the ST's for practice. I'll buy a box from you and try them out in my R9, I'd like to see the results.