These are Acorn Nut Screws. They are also referred to as "Luke Rivets" for knife handles. This version is 0.250 inch diameter with brass heads.
Acorn Nut Fasteners - Luke Rivets for Handles - (.250HD x 8-32US x 1L) - Brass
Guard - Braided Knot - (1-1/8 x 5/8 x 3/8) - [0.4 x 0.085 slot] - Nickel Silver
Acorn Nut Fasteners - Luke Rivets for Handles - (.312 HD x 8-32 US x 1 L) - Stainless Steel - (10 Pk)
HOLSTEX™ - DIY Thermoform Sheet - Carbon Fiber/Tactical - (Armor
KYDEX™ Sheet - Coyote Brown - (.080) - (1ft x 1ft)
Chicago Screws - Black Oxide - #8 - (.203 x .250) - (10 Pack)
Mardatt 100Pcs 7 Sizes Hex Acorn Cap Nuts Assortment Kit M3 M4 M5 M6 M8 M10 M12 Nylon Female Thread Bolt Cover Cap Dome Nuts for Protection, Indoor and Outdoor: : Industrial
Guard - Braided Knot - (1-1/8 x 5/8 x 3/8) - [0.4 x 0.085 slot
6-32 - Set Screw - Stainless - (.250) - (10ct)
CKK Industries
Cap Nut - Satin Nickel