As Sapper mentioned, that was the M21, which was not a particularly good sniper rifle, but not necessarily a bad one either. It was much more adept to the role of Unit Sniper or Designated Marksman like the Russians do. (I�ve always thought the Russians made much better use of their snipers than we did.)
It consisted of a match grade M14 with a 3-9 ART (auto ranging telescope) scope (Leatherwood or Redfield) The barrel was a standard weight (later ones finally started using heavy barrels) that was air gauged and set aside to skip the chrome plating process. The gas piston was modified, the flash suppressor was opened up, the trigger was tuned to 4.5lbs and the action was glass bedded to the stock. These rifles would hold right around 1.5� for 10 shots at 100 yards. Some shot better and some not quite so good, but for the most part, it made for a very good DMR rifle. In the role of a lone �hunter� type sniper, it left much to be desired.
The M21 was replaced by the M24 which never has been a custom rifle built by the AMU. The M24 is an out of the box solution provided by Remington and comes as a complete system �kit� including scope, accessories and case. This is not to say it�s not an accurate rifle.
On the subject of stocks made for open sights, they didn�t exactly correct this with the M24 as it was built to be used with accessory open sights. Most US Army snipers in the field have taped up the comb of the stock to raise the cheek.
Currently, the M14 has found new life in the DMR role. Most are not accurized in any way, but are equipped with a Leupold 3.5-10x scope. Reports I get are that they are very well received.
Several of the special ops units have been using the Knights Armament SR25 (AR-10�ish) with good results. I know that the idea of returning to the semi-auto sniper rifle has been kicked around for some time.
On the M16 side, there have been several accurized versions for use as a DMR rifle. The most notable is perhaps the Mk 262 used by the Navy Seals in conjunction with Black Hills Match ammo.
As an ongoing project, the US Military is actively seeking a replacement for the M16 and the replacement will most likely have a �sniper� version as well. Most RFP specifications call for the ability to change the weapon to support:
Rifle
Carbine
Squad Auto
Marksmans Rifle
The SCAR project (recently awarded to FN) actually broke this down into two weapons, a large (.308 size) and small (5.56 sized). The FN SCAR can switch barrels and cartridges quickly and easily.
Still, the ill conceived (IMO) OICW (Objective Individual Combat Weapon) with it�s .223 backup to the main 25mm grenade launcher program is still alive and well. Who knows how that will factor into the future (my hope is that it wont). This is something that�s into early prototypes and the last I�ve heard, they�re looking for more flexibility and different versions.
Since there�s a Marksman�s version of the SCAR and there�s supposed to be one for the XM8 project, I doubt the military will be adopting (on any significant scale) any of the AR10 variants�Who knows?
