Screws have changed over the years. Vintage Fender use steel screws plated in Nickel. Today's screws are often made of pot medal, heads flatter, and smaller in size. Pictures tell a thousand words. One sure way to spot a fake Stratocaster for instance is neck screws. 1950's - Late 60's Strats and Teles are ALWAYS 2" screws. Never did they use 1.75" as is the standard today.
Another warning sign is pickguard screw heads that appear to sink into the guard, like they are a little to small. This is because they are a little to small.
Our NOS screws are the proper size
Neck screws comparison. Note length and head size/shape. More "dome" to vintage.
#5 Jack Screws
NOS Partial thread set
NOS Full thread set
NOS Tuner Screws. Used by kluson thruout 50's and 60's on many makes and models.