Technical Reference · March 2025

Red Dot Mounting Screws
Size & Torque Guide
for Glock Slides

March 14, 2025 · Trijicon · Holosun · Leupold · Legion Precision Weapon Systems

Mounting a red dot to a Glock slide looks straightforward — until you strip a thread, damage your optic, or lose zero because the wrong screw was used. This guide covers the exact screw sizes, thread pitches, and torque specs for the most common optics on Glock slides so you get it right the first time.

15
in/lb
Standard Torque Specification
15 inch-pounds is the recommended torque for red dot mounting screws on Glock slides across all major optic brands. Always use a calibrated torque wrench — never hand-tighten to feel. Overtorquing damages slides and optic housings. Undertorquing loses zero under recoil.
Section 01
Screw Size Reference

Mounting Screw Size Reference

Screw size and length vary by optic. Using the wrong length can cause the screw to protrude into the slide and interfere with firearm function — a serious safety issue. Verify your specific slide depth before ordering screws.

Optic Screw Size Notes
Trijicon RMR / SRO
Holosun 407C / 507C / 508T		 6-32 × 3/8″ Full-size footprint. Verify screw does not protrude into slide and interfere with firearm function.
Holosun 407K / 507K 6-32 × 7/16″ Compact footprint. Shorter than full-size despite longer nominal length — verify depth on your specific slide.
Leupold DeltaPoint Pro Read Notes 6-32 × 1/2″ Right side screw must be filed down to clear the extractor plunger assembly on Glock pistols. Do not skip this step.
Leupold DeltaPoint Pro — Critical

The right side screw must be filed down before installation on Glock slides. Failure to do so will cause the screw to interfere with the extractor plunger assembly, creating a dangerous malfunction condition. Do not install the DPP without addressing this first.

Screw Length — All Optics

Screw length requirements vary by slide manufacturer and milling depth. Always verify that your screws do not protrude into the slide before live fire. A protruding screw can interfere with internal components, cause damage, and create unsafe conditions. When in doubt, consult a qualified gunsmith.

Section 02
Torque Specifications

Torque Specifications

Correct torque is non-negotiable for a reliable, zero-holding optic mount. Both extremes — over and under — cause failures.

Standard Torque — All Listed Optics

15 inch-pounds (in/lb) is the recommended torque for all red dot mounting screws listed in this guide. Use a quality calibrated torque wrench. Never estimate torque by feel — even experienced gunsmiths use a torque wrench for optic screws.

Section 03
Installation Protocol

Mounting Best Practices

  1. 01
    Verify Compatibility
    Confirm your slide is milled for the specific optic footprint you're mounting. Do not assume a "close enough" fit — footprint dimensions and screw hole positions vary between manufacturers even on visually similar cuts.
  2. 02
    Clean All Surfaces
    Clean the slide mounting surface and the underside of the optic with isopropyl alcohol. Remove all oil, debris, and carbon before applying threadlocker or seating the optic. Contamination prevents proper thread engagement and threadlocker adhesion.
  3. 03
    Apply Threadlocker
    Apply a small drop of blue threadlocker (Loctite 243 or equivalent) to the screw threads — not the mounting surface. Blue compound allows future removal without heat. Do not use red (permanent) threadlocker on optic screws.
  4. 04
    Torque to Spec
    Use a calibrated torque wrench and tighten mounting screws to 15 in/lb. Tighten in an alternating pattern if using two screws — snug one, then the other, then final torque both. This ensures even seating and prevents optic cant.
  5. 05
    Allow Cure Time
    Allow threadlocker to fully cure before live fire — typically 24 hours for full strength. Check your specific threadlocker product for exact cure times. Do not zero or shoot the optic before cure is complete.
  6. 06
    Check Periodically
    Re-check torque after the first 200–300 rounds and periodically thereafter. High round count, steel-cased ammunition, and +P loads accelerate screw loosening. A loose optic screw is a zero problem — catch it before it becomes one.

Need Your Glock Slide Optic Cut?

Legion Precision offers precision optic cuts for Glock slides. Tell us what optic you're running and we'll machine the correct footprint to spec.

Shop Machining Services Contact Us

Always follow the manufacturer's instructions for your specific optic and slide. If you are unsure about any aspect of the mounting process, consult a qualified gunsmith. Firearms are dangerous tools and should be handled with the utmost care. Always comply with all applicable local, state, and federal laws.