I've got an S&W M&P15 chambered in 5.56. I'd like to purchase a silencer for it, while we can.

Can I purchase any silencer for 5.56 and screw it into the barrel after removing the stock flash hider? Sorry, I'm new to silencers.

Thanks!

If the silencer has what is called direct thread attachment, that is how it will work -- straight on the muzzle threads.  Many also come with a special flash hider/comp that has quick attach provision, in which case the can goes on over the muzzle device and is quicker and easier to take on and off.  Many of the better silencers will have interchangeable rear caps, so depending on which one you use they can be either direct threat or compatible with a QD muzzle device.

Thanks. I see that some of the higher end ones have their own flash hider and QD. And I wasn't sure if the flash hider would screw directly onto the standard threads.

Thanks for your help!

Go to the suppressor section and you can find all kinds of info, its located under the Armory button on the tool bar.
http://www.ar15.com/forums/f_6/20_Suppressors.html

Silencer shop out of Austin has a good selection, and generally pretty good prices. I met them at a dallas safari club show earlier this year. Seemed to be pretty good guys. They offer a good selection of direct threads and QD's.

Go over to the Armory subforum and the Suppressor sub, sub forum, spend a little time over there reading up on them and you'll start to get a feel for what will best meet your needs.

I say spend the time learning about them because a suppressor is pretty much a lifetime purchase and you don't wanna rush into getting one that doesn't meet your needs.

I started of with a qd 5.56 can and it is awesome, but now I find myself wanting a real light direct thread can, which will stay on one rifle full time.

When SilencerCo is an option, SilencerCo is usually the answer.