Well, I did some marking on my SD9VE slide and the U-shaped slide stop with "stock S&W guide rod/spring" and Galloway #17(stock factory weight) SS guide rod/spring.

With the redneck testing of both, I can see without using calipers that the Galloway setup is around 1/16th too long in the spring, which doesn't let the slide come fully back to the slide stop U-trough block.

I also compared the springs between stock and Galloway(without disassembling from rods). The Galloway spring rises in a more sharp, spiral angle, and is also thicker spring steel compared to stock. Again, this is with the SD9VE, so I can't compare to how the SD40VE is.

This spring thickness in Galloway could account for the "has come to light" problem that we're commenting on, compared to the thinner and possible shorter "stock spring" used by S&W.

I'm going back to my stock guide rod and spring setup until this gets cleared up or fixed by Galloway, by way of new shorter spring to not cause coil compression-stacking.

I suppose I could remove a coil by Dremel and test to see if that relieves the spring compression length stacking, but I would like to see if Galloway has a better fix.

I'm not a gunsmith, but I've worked on guns for years to repair or upgrade and confident what I can do, but I'll wait for now to see if anybody has/found better solution.