The Colt .45 M1911 was the principal sidearm from of various law enforcement agencies from 1911 to 1985. The Glock is now popular with several police force units but the M1911 still has its fans and may yet see a resurgence.
The M1911 pistol was designed by John Browning. It was the first self loading pistol adopted by the United States Army and served as its principal sidearm from 1911 to 1985. It continues to be used in limited deployments.
The Glock was designed by Gaston Glock for the Austrian pistol trials of 1980. It is the current sidearm of numerous military and police forces worldwide.
The 1911 is an all metal (usually steel) single action pistol using a firing pin. The Glock utilizes a steel slide and barrel, while the frame is space age polymer with metal inserts for stiffness. it uses the "Safe action" trigger system and a striker.
Both pistols use the Browning's short recoil system. The M1911 uses a removable bushing for forward lockup, a swinging link for barrel movement and lugs machined into the barrel and slide for rear lockup. The Glock uses the Browning-Pettier system with a cam for barrel movement and a block in the ejection port for rear lockup.
The 1911 has also been chambered in: .22 Long Rifle, 9mm Parabellum, 38 Super, .40 S&W, 10mm Auto, and many others. The Glock has been adapted to fire: .22 Long Rifle, .380 ACP, 40 S&W, 9mm, 10mm Auto .357Sig, and .45GAP.
The 1911 has been nearly universally lauded for its "crisp, clean" trigger, its intrinsically pointable grip angle, and its slim profile due to its single stack magazine and removable stocks. The 1911s strengths are also its weaknesses, the slim magazine is low capacity and the single action trigger necessitates a manual safety. The Glocks handling has generated more controversy. The trigger is sometimes called "spongy" and the heavier "New York" triggers are little liked. The double stack grip may be uncomfortable for shooters with smaller hands, and the grip angle has been called "awkward". The Glock lacks a manual safety which makes it easier to deploy, and the larger magazines mean fewer reloads and allow more ammunition to be carried. The Glocks polymer construction makes it easier to carry but may increase felt recoil somewhat.
Both pistols are regarded as being very reliable. The 1911s produced for the military are especially well regarded due to stricter interchangeability standards and quality control as well as, counter intuitively, the somewhat looser tolerances required by wartime manufacture. The last military 1911s were produced in 1945 and were still in use in the 1980s. The Marine Corps was reusing WWII era guns to produce its MEU(SOC) pistols into the 90s. Due to the fact that the 1911 was designed to shoot a single bullet profile it may prove unreliable with different bullet shapes or weights. Commercially produced 1911s can vary widely in quality of manufacture and reliability. The Glock is spared many of the 1911s issues thanks to its single manufacturer and 70 years of advancement in design. It is not without its problems, though. The most widely reported issue is with the Glocks unsupported barrel and high pressure cartridges such as the 40 S&W. Case head ruptures causing damage to the gun and injury to the shooter have occurred. Glock has attributed this to user reloaded ammunition, or modification to the gun, but it has happened even on unmodified pistols using good quality factory ammunition.