how to fix screw thread?

[majormarine]

i just wonder, if possible, how to fix screw thread?

not the thread on the screw, but the thread on the other piece where the screw is going to make contact.

 

[gunasauras]

Drill it out and tap it a larger size, install a helicoil(not likely on guns), plug the hole, re-drill it and re-tap it, or weld the hole, redrill it and re-tap it(not on barrel or receiver or bolt though).....I think that pretty well covers it...

 

[Plinker]

How bad are the threads? If they're only a little bit messed up, you could "chase" them with the correct size tap, and that might solve your problem.

 

[Ripstop]

If all the threads are still there but the fit is sloppy, you can use a steel bearing about 1 1/2 - 2 times the diameter of the screw. Place it on top of the hole and give it a tap with a small hammer. This pushes down on the first couple of threads and tightens them up. This is in no way as good as helicoiling or weld/plug and re-tapping but it's easy to do and if the threads aren't that far gone, just might do the trick.

In some of the crappier machine shops, this is what they do so the no-go gauge doesn't drop to the bottom.

Ripstop