Cleaning and chasing scope mount screw threads

[MS50]

I removed the scope and rail from a Mod12 to install a new barrel, stripping the heads of the screws in the process. I have spares. Blue loctite was used. The threads are pretty packed with the dried yellow/brown loctite. I want to chase the threads with a 6-24 tap, but getting it started didn't go well. I tried bore cleaner and alcohol to hopefully loosen the dried loctite, with little success. I have used a tap before, but the threads weren't nearly as caked as these. What can I do to soften the dried loctie? I know that some use no thread locker on their mount screws, but I'd like to use it. Has anyone used purple loctite on their mount threads with success? What about just using an anti-seize compound? Thanks.

[NF1E]

A little heat applied should soften the loctite enough to remove it with a Qtip. Were you going to use a thread chaser, or a tap?

[MS50]

I have a tap. After a search, I see the difference between the tap and chaser. Looks like using a chaser runs a lower risk of damaging the threads. I'm in no rush to complete this task, so I'll get the appropriate tool to do the job. I'll also continue to work on removing as much dried loctite as I can. Thanks for the feedback.

[MS50]

Correction - I have a 6-48 tap, not 6-24.

[NF1E]

Yep, a chaser will be a step toward saving a Bubba and have to go to larger threaded screws. Learned the hard way myself. Whatta Hobby!

[Blue Avenger]

not as good as a proper tool, but you can cut a slot in the tip of a screw and clean threads

[Dave Hoback]

Let me ask you a question: When you say it’s having trouble getting started, do you mean by simply twisting with your Thumb & Finger? If so, it’s because twisting just that tiny 6-48 Tap with your fingers does not generate enough rotational Torque to cut through & push the old material. However, that can be easily remedied with a little homemade Torque Multiplier. I made mine with a 1/8” Drill Stop. (I drilled mine out with #25 Cobalt drill bit because I have them, but the 1/8” works just fine by spreading it open slightly more with a flat blade screwdriver.) Now, my 6-48 Tap measures .136” on the round Shank. (Not the square drive portion). This gives ample amount of torque without being enough to strip the threads. Works perfectly. And, you’ll likely have better luck finding a cheap 1/8” drill stop over a 6-48 Chaser tool! And I guarantee it will be cheaper! I purchased a set og these drill stops fit like $6 from Amazon.

[charlie b]

When chasing threads I like to use a spare screw with the end notched as mentioned above. I don't slot it all the way through, just a small notch leaving the 'cutting edge' at around 90deg. I just get antsy about cross threading using a tap. Takes a good feel and sometimes I don't have that. I do like Dave's collar. Nice trick.

The good part is.....if you mess it all up you can just go to 8-40 screws :)

[MS50]

You're right Dave, I could not find a 6-48 chaser. The drill stop looks like a good idea, I'll look into it. I'm certain I ran the 6-48 tap into another receiver, but it was not SS. As you say Charlie, I was pretty uncomfortable with the process, although it turned out alright. For the Mod12, I cut 17cal patches, stuffed the pieces into the screw holes with a probe, and soaked the patches with Hoppes Elite and Kroil. After a few hours, I screwed a beat up rail screw into the threads and backed it out. The chunky Loctite residue was gone. Viewed through a lighted magnifier, the threads are stained yellow, but there is no residue. As far as tapping the threads for 8-40 screws, I hope I don't ever have to go there! Thanks to all for the feedback.