I can not get the small (3/8?) nut that attaches the toilet braied metal feed line to the cut off valve to stop leaking. I am using 2 turns of teflon, hand tighthen and then 1/4 of a turn with a wrench. It leaks. I tighthen a little more, it leaks a little less but still leaks. I tighthen even more, it leaks even more. What to do next? Use paste instead of teflon? File smooth the end of the valve so it sits better in th O ring in the nut of the braided line?
Use a different feed line?

Thanks!!

Loose the teflon tape. You only use teflon tape on NPT fittings. Tighten finger tight and then no more than 1 turn.

I use some silicone grease on the threads so it can be disassembed much easier later, but it's not required either.

Tighten the nut another full turn, maybe a turn and a half. Forget the Teflon and pipe thread sealer, they are for making water tight connections between threads. The braided supply lines have the "O" ring for that. Just tighten

Loose the teflon tape. You only use teflon tape on NPT fittings. Tighten finger tight and then no more than 1 turn.

I use some silicone grease on the threads so it can be disassembed much easier later, but it's not required either.

Can I reuse the same Braided line? (I read I need to get a new one)

Use the one you got.

Like KISS said, No Teflon Tape on the threads.Use the same supply but make sure the "O" ring's in the correct position and not nicked or split. Good luck, Tom

Harold said? What about me? No one notices? Story of my life?

A thousand apologizes KISS. You said it first! Go back and read!! Cheers, tom