The Difference Between M21 and M1a Rifles | M1A Rifles | M1A Forum

If you we're to choose between the two which one is it?

Mine would be m1a. Its more accurate for me than the m21 that goes left or right when firing.

Post edited 7:36 am – December 3, 2011 by Real Sniper
Post edited 7:38 am – December 3, 2011 by Real Sniper
Post edited 7:49 am – December 3, 2011 by Real Sniper

I trained on the M21 and was able to hit targets out to 1,100 yards with ease.  It was matched with the 3x9 ART (Automatic Ranging Telescope) scope, which had a ballistic cam calibrated for the M118 Special Match round.  The reticle had vertical stadia lines which were set for 30".  Top of the head to the belt line is about 30".  Therefore, the sniper would adjust magnification to have the stadia lines on the top of the head the belt line,  Changing the magnification would adjust the scope so the center of the reticle (where the lines meet) would be where the bullet would impact.  This worked for ranges from 300 – 900 yards. Outside those ranges good ole Kentucky windage came into play.   

Not to cause a ruckus, but some items I take exception to in the original posted information:

The M21 rifle is a rifle based on the M14 rifle and was the primary Army sniper rifle for the Vietnam War till it got
replaced by the bolt action M24 Sniper Weapon system in 1988. The M21 accuracy is about 750 yards (actually accurate out to 1,100 yards or more depending on who's on the trigger)  and uses the US match grade M118 NATO 7.62 cartridges in five-round (never saw a 5 round magazine in the Army) or 20-round magazines. With the immense accuracy, the M21 can fire at long-range ball and ball/tracer and armor piercing ammunition. Its long-range ammunition produces stringent tolerances to ensure superior accuracy.

It is the ultimate rifle that has auto-loading accuracy and in active duty, is has elite spec-ops groups world-wide. The M21 is classified asthe ultimate tool for those entire law enforcement sharpshooters. The rifle is equipped with an adjustable cheekpiece stock, which enables it to maintain its perfect head alignment with the scope. Known for being
accurate, reliable and powerful, the M21 rifle remains the world class standard for sustained precision fire.

On the other hand we have the M1A. In a nutshell, the M1Ais a high-quality reproduction of the U.S. M14 rifle which was used in the early years of the Vietnam War. First is was criticized as being outdated but with its re-introduction in 1957, the M1A (the M14) remains in service today with certain U.S. Army, Navy, and Marine units as well as
other law enforcement units around the world.   The Springfield M1A capitalizes on the popularity of the M14 type by using GI parts and specs. (The M1A is the civilian version of the M14.  The M1A is not in service with the military, but the M14 is.) This rifle is gas operated and comes in a military style configuration. The Standard model of the M1A costs around $1000 whenpurchased on an online auction site and it is classified as an assault
weapon if equipped with a pistol grip or flash suppressor in several states.

The obvious differences between the M21 and the M1A are the M1A has a vertical recoil system whereas the M21 can move to the left or right while firing. (???) The M14 holds more bullets, but more damage is done by the M21. (Not correct.  They hold the same. All depends on the magazine) Also, the M1A is a semi-automatic/automatic
rifle (M1A is semi-automatic only.  The early M14 was select fire, but they then had the selector switch welded to the semi position.  The M14E2 was a fully automatic version of the M14 and was used for a short time as a Squad Automatic Weapon) while the M21 is a modified version of the M14 which is especially built for sniper activity.

From Snipercentral.com

"The M21 is essentially a modified M14 National Match rifle. The earlier versions (XM21) had a specially selected walnut stock, but this changed with the M21 to a fiberglass stock, often camouflaged. The XM21 began to be fielded in the second half of 1969 and remained the U.S. Army's primary Sniper Weapon System until it began to be replaced by the M24 SWSin 1988. Some National Guard units and even a few active duty units (The OPFOR at JRTC for example) still use the M21. The M21 is a very practical sniper weapon maintaining acceptable accuracy out to about 700 meters. Besides the problem that it is semi-auto and sends brass flying, the M21 was, and still is, a very capable military sniper rifle. The 10th SFG, in conjunction with the U.S. Navy SEALs has developed an improved version of the M21 known as the M25. The M25 was designed out of a need for a semi auto sniper rifle, and it was the weapon of choice for SEAL snipers during Desert Storm. The M21 holds a dear spot in many U.S. Army snipers hearts (me included), and rightfully so."

Wilkipedia

The United States Army wanted an accurate sniper rifle during the Vietnam War. The M14 was selected because of its accuracy, reliability, and the ability for a quick second shot. As a result, in 1969, the Rock Island Arsenal converted 1,435 National Match (target grade) M14s by adding a Leatherwood 3–9× Adjustable Ranging Telescope and providing National Match grade ammunition. It was designated the M21 in 1975. The M21 remained the Army's primary sniper rifle until 1988, when it was replaced by the M24 Sniper Weapon System; some M21s were later re-issued and used in the Iraq War.^[1]Vietnam War era sniper rifles, US Army XM21 (top) and USMC M40 (bottom)

In standard military use, the M21 uses a 20 round box magazine as the other members of the M14 family and weighs 11 pounds (5.27 kg) without the scope. The U.S. military never officially authorized or purchased magazines in any other capacity, although 5- and 10-round magazines are available.

Early M21 with ART II Scope

M14E2