Were you talking about a noise supressor? If so then your talking about federal permits, extra fees, and for a .308 that sucker would be like 18" long on the end of the barrel. Look how long they are just for a 9mm, they are as long as the handgun itself. And then if you still want a noise supressor, everytime you move your residence you have to notify the govt that your moving or more importantly that the supressor is moving. They like to know where firearm supressors are located throughout the US.
Now if you were talking about a flash supressor like what is on a M1 or AR15.... They do not increase accuracy, and can actually very easily hurt accuracy.
Look at all the bench rest rifles (those are as accurate as you can get, they are sub .3 MOA easily) or accurate hunting rifles. They have recessed crowns on the muzzle end kinda like on our FNAR's. The crown has to be even, smooth, and nick free 360 degrees around or the escaping gas will have an extra push against a side of the bullet as it leaves the barrel where there is a nick or ding. That slight gas pressure will affect accuracy of the bullet. This 360 degree nick free environment is hard to have when you have a flash supressor that has six or eight openings to spread or supress the flash.
This is why everyone needs to be very careful when cleaning the bore with one of those common steel cleaning rods and never bang the muzzle with it. Especially when pushing the brush down the barrel and then the brush exits the barrel into the chamber and all resistance is gone and your still pushing hard to get the cleaning brush thru the barrel . And never never put the muzzle down on the ground!!!
We have an accurate rifle (or any other rifle with a recessed crown on the muzzle) but it will require some TLC to keep it a tack driver.
clean FNAR bore from chamber-end with flex cable pull-"
Something I picked up from member ARLover over on thehighroad.org forum: Pull brushes, patches, etc. through from the chamber using an Otis product like: http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=348653
I got one. Costs < $10 and has some of the end-hardware you need. Both ends have 8-32 female threads to accept accessories. Someone mentioned a "T"-handle to put on the fished-through end to aid in pulling. I haven't seen where to buy that, but no big deal.