Here's an experience of mine that may help others.
When I bought my second Jackson Kelly some 15 years ago or so, I decided to go with a much lower tuning than I was previously used to. The problem was that the much heavier string gauge I needed to use made the locknut screws almost too short. Almost. There was still a thread or two to lock it down, but that's asking for trouble. There is absolutely no need to tighten these nuts down so hard they flatten the strings. Just snug enough that they won't loosen by themselves, but even repeated "just snugging them down" over the course of several string changes will wear the available two thread turns into something useless.
The trick (if you could call it that) is to take one of those screws down to a hardware store or fastener shop that you know will have a decent supply of the not-so-everyday-use fasteners. Find one of the exact same style head, diameter, and thread count but make sure it's just a bit longer in length. You don't want it get one that's so long it bottoms out and causes other problems.
Here's a comparison pic; stock size on the left, new size on the right:
![](http://i270.photobucket.com/albums/jj118/casey71us/guitarstuff002.jpg)
Now here's the pic with the screws inserted in the clamps. New one on the left, stock on the right:
![](http://i270.photobucket.com/albums/jj118/casey71us/guitarstuff003.jpg)
If I had used a segment of guitar string (which I should've) in this pic back when I took it, you would definitely see that the string thickness will affect how much of that locknut screw is or isn't actually getting a good thread engagement. It wasn't so much a problem with lighter 42-46 strings, but 52 made it obvious that the screw and locknut base wasn't going to last for very long. And I only needed one new length screw for each guitar instead of replacing all three because the other 4 higher thinner gauged strings already worked out fine....just the lowest 2 heavy gauge strings needed the little extra peace of mind.
Of course, there's a lot of differences that may or may not require this "mod". Some guitars might already have an optimal screw length on their locknuts, some may not. But if yours doesn't, this is probably the easiest guitar modification you'll ever do.