Has anyone removed the flash hider from their 556? How? Which way is it threaded, conventionally?
Thanks, Peter.

If the barrel is sixteen inches, I'd grab it with a strap wrench and give it an anti-clockwise twistin'. I'm gonna assume it's a US-made gun, so the threads will most likely be right-handed...

I assumed right handed too, but it is not budging and I don't want to wreck anything! SIG doesn't seem to have an email for customer service.
Peter.

Might be pinned and the pin camouflaged. Could be silver-soldered. If it is, that requires the barrel to be heated to near 1000 degrees (I'm guessing-- maybe higher) and have the flash hider turned off. Of course, heating it up that high will trash the finish and may alter the heat treatment. I ain't no metallurgist. I'm postulating. Just seems to me that heating the tip of the barrel way up like that has got to do things to it. I counsel you keep researching. Try other sites dealing with military-heritage weapons for civilians...

If the length of the barrel itself is 16" plus the flash hider, one would think it is removeable;however, if the barrel's length is made legal by the addition of the flash hider, it will be permanently attached. You could insert cleaning rod down bore, with bolt closed, and see if the end of the barrel, (just behind the FH) is truly 16" and if not would say it is pinned and silver soldered and not intended to be removed or shall we say not easily.

Hmmm, hadn't thought of that. The base of the flash hider is round with two flats, so I assumed that it acted as a nut, but I don't know whether it is the base of the flash hider or part of the barrel or just a "lock nut" type device. Guess I will have to call SIG and wait on hold for an hour!
Peter.

Problem solved! I took it to a gunsmith!
Peter

Was it just tight or otherwise fastened?

Tight. I finally called SIG and they said it was put on tight and that I might want to get special tool that they thought Brownells sold (but they didn't). Bear in mind that some guns (including SIGs?) may not have a removable flash hider as that appendage may be necessary to make up the 16" barrel length. Mine is not the SWAT model.
Peter.