Witness Marks on Screws


I use a simple sharpie marker in silver color. This generally isn’t in an area that gets a large amount of friction, so there’s not a lot of risk in it rubbing off. For those that really need EVERYTHING to be subdued (you know who you are), I use a red sharpie.Here’s a couple examples: the silver is on my personal weapon, the subdued is on a work rifle.

Scope Ring Marks

Scope Ring Marks

Witness marks can help by providing a visual indicator when a bolt/fastener comes loose. Witness marks also help you provide the same torque when a torque wrench isn’t available or practical.

Red-Dot Base Marks

Red-Dot Base Marks

I did this a while ago with my duty rifle, PRS guns, and a switch barrel gun I use (LMT MWS)



Editor’s note: Kelly sent this over a while back, but I am so unorganized, I kept dropping it. How? I always want to wait for the “perfect” time to post things. Then it falls through the cracks. Obviously I need to find a better solution. My apologizes to Kelly for the delay. —Marky

Marky Mark

Marky Mark

Writer at John1911.com
Writer for john1911.com. Co-Host of the John1911 Podcast. Video content provider for John1911-TV.

Areas of focus: Defense and National Security, Modern Light Weapons, Analysis of the Geo-political / Military Relationship in the Context of Strategic Goals.
Marky Mark

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  • Conner

    I almost feel dumb not to have been using these witness marks in my years of working with firearms. Very simple and effective. Good thing I found this out now at the spry young age of 62. Thanks Kelly and Marky.

  • Brennen Munro

    We could always use the aviation model… everything that needs to stay screwed or bolted gets a fastener with a hole in it’s head, screw or bolt, and is then it is wired to something else making it more or less impossible to back out. It is a major pain in the ass to work with sometimes, but it works very, very well!


    • It’s like the scene from the Godfather….

      Just when they made a 308 battle rifle that is lightweight, they pull me back in!!!!