[Brad4]

I am in the process of installing a Lyman peep sight on a Marlin 336. One of the factory tapped screws was easily removed; the other has refused to budge. I have tried various hand methods and am afraid that I might strip the screw head if I continue to try to force it out. Any suggestions would be appreciated.

 

[Skipper]

Try some low heat (depending on material) or soak it with Kroil for a few hours.

 

[Goatwhiskers]

An excellent penetrant is a 50/50 mix of acetone and ATF. To keep from stripping the slot out chuck the correctly fitting screwdriver bit in your drill press, lay the gun on the table and lower the chuck until the bit is firmly seated in the slot, then hold it down firmly and turn the chuck by hand in the proper direction. Usually works. Goatwhiskers the Elder

 

[unclenick]

I once had a shop tell me the rear alignment of my car was off a little, but that they couldn't correct it because the rear adjusters were frozen. It wasn't severe and the tires were due to be replaced, so I left it. Then, when new tires were due, which included a free alignment, three days before the appointment I started reaching under the car and spraying the adjusters with PB Blaster once a day. When I picked the car up with its new tires, I asked the mechanic who'd done it if he had any problem with the frozen rear adjusters? "What frozen adjusters?"

Whether using Kroil or PB (which smells bad, but works), a couple or three days pre-soak with once or twice daily reapplication is a good plan. Just avoid getting them on the stock finish, especially the PB, which is orange and can soften some finishes and can stain.

The heat may help too. If you wind up tearing up the head, you may need to get an EZ out (but check this information before using one) or a Grabit.

 

[au2183]

I use PB Blaster too, that I buy at NAPA. It works better than any other penetrant I've ever used.
Goatwhisker's drill press trick works real well too.
If neither one of those work I use a left hand drill bit as a last resort. Buy one slightly under the thread size, again in a drill press if possible, real slow, and it will often back the old screw right out.
Good luck!

 

[Cheezywan]

Patient application of penetrating solvent has worked well for me mostly.
Sometimes applied on a time-table (such as morning and evening) over several days as needed.

Example that sort of fits your trouble Brad4:
A drop twice a day on top of the screw you are working.
Keep that up until you “see” the bottom of that screw get “wet”. (Now you know that the solvent has “penetrated”.)

Put a drop of gun oil on that screw every day until you can’t stand it anymore.

Put a proper fitting blade in the screw slot and give it a “sharp whack” on the handle with a mallet.

One more drop of oil and wait a year (more or less depending on the screw).

Proper blade and turn out screw.

Oil will mix with solvent if given enough time!

Cheezywan

 

[StretchNM]

I'm a believer in heat. Soldering iron right on top of the screw head. This softens the threadlock on the threads.

 

[Brad4]

Gentlemen,,,thanks for the advice...got it out with a combination of PB Blaster and hair dryer... and swearing. I do appreciate the expertise available on these various forums. Thanks again.