First and formost, I have to say, this is the crim de crim of gun forums, bar none. Considering my lack of posts, I must admit that when I login, I find my answers and get out. If I DO, find anything interesting or noteworthy, I assure you, I will post it.
On with the show...

I have a BM M-4 type carbine that I am considering replacing the FS on. It is a "post ban", obviously, and has the pinned FS from factory. If I remove this FS and find that the barrel is threaded, can I replace it with a threaded "pre ban" FH if the AWB sunsets in a few days? Does this replacement have to be pinned and permanently attached after the sunset on the 13-14th? Or is the barrel length part of a different law all together?
I noticed within another thread that a fellow removed his mini Y-comp FS and the barrel was, in fact, threaded. I would like to do the same, if the barrel is threaded as I may, in the future, purchase a silencer (registered of course) for use with the barrel.

Any thoughts on this?

Thanks in advance for any response.

jnp

First of all your barrel needs to be 16" unless you want to register your lower as a Short Barrel Rifle and pay the $200 tax.

If you remove your FS and your barrel is threaded then you can easily replace your FS.  However, if, with your FS off, your barrel should measure 16".  If it doesn't you will have to permanently mount a FS long enough to make your barrel 16".  A GemTech BiLock mount is long enough to do this and will allow you to use a suppressor.  If your barrel is 16" you can go with any thread-on suppressor.

You must permanently attatch the flash suppressor in order to make your M4 barrel 16 inches long.  Yes, the barrel length is part of a different law - 1934 NFA.

I would recommend the Vortex by Smith Enterprise.  The best of the flash suppressors in terms of actual elimination of flash.

Damn quick. Thanks pazzo.

So, in other words, my 'pinned on" FS is the only reason my carbine is legal (according to law other than AWB). If I purchase a 16" barrel, I'm good to go with only a thread protector? As long as the "fixed" barrel measures 16"? Does that sound right, or am I a quack?


Well, I may be a quack, regardless....

Thank you, too, Feedingcannibal.

I wasn't absolutely sure about the length of the barrel being in which law. Thanks for clearing that up.
Now.
Gemtech Bilock mount. Where and how do I find one of those bastards? I could do a search, but where would you guys suggest? Not here in town, none of the shops around here carry the fun stuff.

You got it.  After the death of the AWB, you can have a 16" barrel with a threaded flash supressor skrewed on, or permanently affix a flash suppressor to any shorter barrel to bring it up to the 16" requirement.

This is the reason that many here advocate the 16" barrel - to avoid permanent attachment.  Personally, I want my carbine as short as possible, so I opted for the 14.5" with a permanent flash suppressor.

The Gemtech is designed to accept their silencer, which is an NFA item.  Unless you plan on spending the cash for the NFA tax stamp and the hurdles involved, my advice is still the Vortex.

www.gem-tech.com/m4-96d.html

Personally, I am a silencer junkie.  Why not register your lower as a SBR and get a Bushy 11.5" upper or a LMT 10.5" upper.  I use the LMT and like it.  Works great with either a American Manufacturing Triple X Warrior or a SWR SpecWar1 (both thread-on cans).