Retrieving Snapped-Off Screws

Screws snap off when repairing or upgrading a firearm. This article documents the best way I’ve found to retrieve snapped off screws in a gun.

I learned the technique by watching a YouTube video about car engine repair, the source of untold bolts snapped off when torqued too tight. Most of the snapped of screws I’ve encountered have been in rifle scope mounting rails and rings which, come to think of it, requires proper torquing of pretty small screws – a similar screw snapping risk.

My example is a mounting screw for a Picatinny scope rail. It snapped off before I was able to apply the prerequisite torque (I suspected a flawed screw from the factory). The snapped off screw was located in the forward most mounting hole toward the muzzle.

I started by removing the second screw I’ll call the “good” screw from the rail front and used it for depth measurement with the snapped off screw retrieval.

I left the Picatinny rail attached to the rifle by the rear rail screws so that the rail could help guide drilling the snapped off screw.

I retained the top of the snapped off screw to help me remove the bottom of the screw. The top is 13/64” long and threaded 6-48. Here is the top of the screw before starting the retrieval process.

My retrieval procedure started by drilling out the top of the snapped screw to make a kind of mandrel to drill into the snapped off bottom. I use the largest drill that would hollow out the screw but leave the threads intact. In this case, I used a 5/64” titanium coated drill. Here is the screw top drilled out with the threads intact.

Next I marked the same drill bit with the total depth (21/64”) of the rail screw using the “good” screw.

Then I dropped the hollowed out screw top back into it’s hole on the rail, placed the drill vertical to the rifle and ran the drill bit though the hollowed out screw top that is now being held steady in the rail.

Then I drilled down slowly till my drill bit mark just touched the top of the hollowed out screw top. Here is what the drill bit and screw top looked like when the drilling was finished.

Next I used a #2 Irwin screw extractor to back out the snapped off bottom of the screw. Here is the tool in position and the results.

Here is a comparison of the 1st rail hole screw retrieved and the ”good” 2nd rail hole screw.

The last step was to take the “good” screw and fit it into the 1st rail hole to confirm that the threads were not damaged by the retrieval. I’m pleased to report that the “good” screw could be started and tightened flush with just my fingers.

==The End==