An AR15 fitted with a scope.   This is the civilian version of a M16, which is the standard issue rifle in the US Army.  It was manufactured by Colt, with a match barrel and forward assist.  The forward assist is used to clear jams and malfunctions.  The rifle and be "broken" in half for cleaning in a matter of seconds.  All military rifles contain cleaning kits in the rifle butt, however; these rifles have been modified with a hard rubber butt stock for comfort.

A Springfield M1A fitted with a Harris Bipod.

In the above configuration the M1A might be considered a sniper rifle.
It weighs well over 10 lbs.  It fires a standard NATO 5.56MM round.  It can be accurate up to 1000 yards, and with the scope properly sighted, you'll be good for 600 yards (1,800 feet!!) easy.

 A close up photo of the M1A.  The M1A is considered one of the most accurate guns ever made that is NOT a bolt action.  The M1A is a semi-automatic rifle that accepts 5, 10, 20 & 30 round magazines.  The military version is called an M14 and is still used today by many military snipers and police SWAT Teams.  The above rifle is pre-ban so it's fitted with a bayonet lug.

With a standard sling the rifle can be easily be carried over long distances.

The M1A is based on the Famous WWII M1 Garand.  It uses a rotating bolt design and tears down to the above 3 sections without any tools in about 5 seconds.  Although the M1A can get very hot and actually burn your hand if not properly handled, it is air cooled.  The gun smithing tools were required to configure the rifle for a second generation scope mount.