Metallics QK258M 10 x 3/4 in. 1/4 Hex Head Slotted Sharp Point Self-Piercing & Tapping Screws - Steel Zinc - Each

The QK258M ships in box quantity with an order minimum of 8,000 each. It is a bulk-box item, so there is no small count. If you need a different size or a smaller count, Metallics offers other sizes and quantities by request.

No pre-drilling. The QK258M is a sharp point self-piercing and tapping screw, so the point pierces thin metal and the thread forms its own mate as you drive. Twin lead threads cut the driving torque, which matters when you are running hundreds of them overhead into strut, boxes, or sheet metal.

No. The QK258M is listed as not Buy American compliant and not ARRA compliant, with multiple countries of origin. If your spec carries a domestic sourcing clause, this is the wrong fastener and you need a domestically produced equivalent.

Either. It is a hex washer head measuring 0.244 to 0.25 in. across, so a 1/4 in. magnetic hex driver seats on it, and the head is also slotted (slot width 0.045 to 0.054 in., depth 0.052 to 0.074 in.) if you need to back one out with a flat blade. Head height runs 0.096 to 0.11 in.

The head is an integral washer type, 0.384 to 0.414 in. outside diameter with a washer section 0.019 to 0.031 in. thick. No separate washer needed. That bearing surface spreads load on sheet metal and thin plate, and it covers an oversize or slightly off-center pierce.

With a 3/4 in. length and 12 threads per inch, there is roughly a half inch of usable thread once the point and head are accounted for. Metallics also undercuts the area beneath the head, which gives more thread engagement than a screw with a full shoulder. For #10 that puts it in the range for sheet metal, junction boxes, and light framing rather than structural plate.

The QK258M is zinc plated carbon steel, which is a dry indoor finish. It will handle an occasional damp interior, but for exterior, coastal, or wet locations you want stainless or a coated exterior fastener instead. Keep these for inside work: panel and box mounting, duct, hangers, and interior metal-to-metal.

They are made to AISI 1018 to 1022 low carbon steel, case hardened to Rockwell C28-38. That is enough surface hardness to form threads in sheet metal while leaving a ductile core, so the shank is less likely to shear than a through-hardened screw. It is not a self-drilling point for thick plate, though, it is a sharp piercing point for thin stock.

Treat them as a guide. Metallics states outright that head dimensions on self-piercing screws differ from standard tapping screws, and that there is no single industry standard for self-piercing screw dimensions, so deviations from the listed ranges can occur. That is why the head width, height, washer, and slot figures are given as ranges rather than single values. If you are matching an existing run visually, the 1/4 in. hex washer head is the thing to match on.