Red Dot Optic (RDO) Replacement Parts

Langdon Tactical

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RDO Replacement Screw Accessory Kit

Please Choose Carefully as the screw lengths for RMR/Holosun, HE509T, DPP/Romeo, Doctor Optic, & Holosun EPS are different, and each kit includes different items! Selecting the Replacement T-Nuts only does not come with any bits or screws, select NONE under RDO Screw Type.

The Screw Kit includes:

  • Thread Locker
  • (2) Short - Holosun to Plate Screw: 4 x 40 5/16 (non-metric), 
  • (2) Long - RMR To Plate Screw: 4 x 40 3/8 (non-metric)

The T-Nut Kit includes: 

  • Two (2) LTT RDO T-Nuts (from C&H Precision) 

The Screw and T-Nut Kit includes:

  • All of the above 

Please choose the correct screws for your RDO Optic Plate: 

  • Trijicon RMR Footprint:  Fits the Trijicon RMR, SRO, and Holosun 407c, 507c, 508T family of optics
    • For attaching a Holosun to the RDO Plate use:  4x40 – 5/16
    • For attaching an RMR or SRO to the RDO Plate use: 4x40 – 3/8
  • Holosun 509T: does not require mounting screws from us. 

  • Doctor Optic: Doctor to RDO Plate use: 4x40 - 3/8 or 4x40 - 5/16

  • Delta Point Pro: Delta to RDO Plate use: 4x40 - 1/2

  • Holosun EPS: EPS to RDO plate use: 4x40 - 5/16


DISCLAIMER: We recommend that this product as well as all other firearms parts & kits sold by Langdon Tactical be installed by a competent pistolsmith. No liability is expressed or implied for ANY damage or injury which may result from improper installation or use of this product. Installation of any firearm parts may limit or void the manufacturers warranty. We strongly recommend that the safety and operation of your modified handgun be thoroughly checked by an accredited gunsmith prior to use.