Saddle screws

Jono111

I want some shorter saddle screws, Amazon has some M3 screws but mine are around 2.78mm wide. Is that a M3 or is it some odd imperial size.

BillDL

What is the make and model of the guitar and is it the original bridge.

USA made Stratocasters usually use imperial size of grub screw that can be UNC #4-40 (rough thread pitch) or UNF #4-48 (fine thread pitch), depending on model.  The diameter of a #4 is 2.85mm and it takes a 0.05" Allen key.

"Import" Fenders or Fender styled guitars made in Japan, Korea, China, etc, including Squiers usually use metric M3 grub screws that take a 1.5mm Allen key.

https://www.westfieldfasteners.co.uk/A2_ScrewBolt_GrubFlat_M3.html

My research has found that the following "rules" apply to genuine Fender Stratocasters, but as we all know rules can vary and it is always wise to check:

Vintage Reissue Strats use Coarse UNC #4-40.
American Standard Strats 1986-2007 use Coarse UNC #4-40.
American Deluxe Strats use Coarse UNC #4-40.
American Standard Strats 2008 and newer use Fine UNF #4-48.

SteveRobinson

M3 threads are generally slightly less than 3mm in diameter