Originally Posted by AznZOhAn
Is there any slop or play in the rail system?
There is no play in the rail system, but like most ARs there is a very slight amount between the upper and lower. They are great guns. Like others have said, they are a little front heavy because of the piston. A lot of sig 516s require a break in period to be able to use steel ammo on the regular setting, but you can always open it up to the largest port if you really want to. Just dont do the largest port with regular or more powerful ammo. It will wear out the gun. Also, the irons on it are OK but not great.