Glock

    The Glocks are series of semi-auto and fully-auto pistols, designed by Gaston Glock.
Glocks are mainly designed by advanced synthetic polymers, and this is what makes it different from other modem firearms.
Dispute facing the initial resistance in the market to accept a plastic gun due to durability and endurance concerns and most of all the fear that this gun would be invisible to metal detectors in the air ports, this gun has proven to be the most profitable products line of the company, since it now holds 65% of the total market share of handguns for US law enforcing agencies. 
These guns are also preferred for self defence use for  civilians as both concealed and open carry weapon.

Second Gen Models:
   A mid life upgrade in the Glock Pistols were introduced in 1988 and were second generation models. 
Additional checkering on the front strap and serrations in the back straps were introduced in them, in addition to a steel plate with stamped serial number was embedded into the front receiver in front of the trigger guard. 
After a while an integrated recoil spring assembly replaced the original two piece recoil spring and tube design. And magazine was also modified with a changed floor plate and a follower resistance spring was inserted at its base.



Third Gen Models: 
   In these models accessory rail was introduced, allowing the use of accessories such as laser sights and tactical lights. Thumb rests on both sides of frame and finger groves were added allowing more user friendly handling.
Modified extractor was also added which acted as a loaded chamber indicator, locking block was also enlarged. 



Fourth Gen Models:
   In 2010 Glock presented the Generation 4 or Gen4 models, in these models the upgrades were centred at the recoil spring assembly. Also all parts of Gen4 Glock's parts can't be mixed and matched with its predecessors. 
The initial models of Gen4 were Glock 17 (9x19 mm parabellum) and Glock 22 (.40 S&W).
On all Generation 4 Glocks "Gen4" is roll marked on the slide next to the model number to identify the generation 4 models.

Variants:
  The Glock pistols have many variants  identified with their number added in front of Glock name. 
like "Glock 17" or  "Glock 18".
All Glocks are almost modelled after the original Full-sized Glock 17.


Glock 17:
  The Glock 17 is original 9x19 mm Parabellum model, with 17 round magazine capacity, many modified versions off Glock 17 were also introduced. 
Glock 17C: This model has slots cut in slide and barrel to compensate for recoil and muzzle rise. Many other glock pistols come with this option all with suffix "c".

Glock 17 Gen4

Glock 18:
    This is a selective fire variant of Glock 17, designed at the request of EKO cobra. This machine pistol has a lever fire control switch on the rear left side of the slide. When the lever is position at bottom, pistol will shoot in FULL-AUTO mode, when its positioned at top, pistol will shoot in SEMI-AUTO mode. It uses 33 round extended magazines of 9mm parabellum, although magazines of Glock 17 will also work.
Glock 18C is a compensator variant of Glock 18 to reduce muzzle rise during full-auto firing. Compensator cuts start about half way back on the top of the barrel. There are 4 cuts, 2 on the rear are narrower then the front two cuts. A rectangular section is dished out on the top of the slide because of these compensators.
At full auto mode Glock 18 can shoot up to 1200 Rounds per minute. 

 Glock 18c top view

Glock 18c left side.

Glock 19:
  It is a compact version of Glock 17.
With effectively reduced size Glock 19 has pistol grip and barrel which are 12 mm shorter then Glock 17.
It uses standard magazines of 15 Rounds, how ever it can use factory magzines of Glock 17 and Glock 18 with 10, 17, 19 and 33 rounds. Just like Glock 17 and Glock 18 it uses 9mm Parabellum bullets.

Glock 20: 
  The Glock 20 uses 10mm auto bullets, and is able to use both standard and reduced velocity rounds. Because of 10mm auto is larger and has higher muzzle pressure then 9mm Parabellum, the Glock 20 is slightly larger then Glock 17, with 2.5mm greater width and 7mm greater length. It has standard magazine capacity of 15 rounds. 

Glock 21:
   Its a .45 ACP version of Glock 20 designed for American market. Except the slide of Glock 21 is lighter then Glock 20's to compensate for lower energy of .45 ACP cartridge. 

Glock 22:
   Its a .40 S&W version of a full sized Glock 17. This gun has modified slide, barrel and frame because of different size and power of .40 S&W cartridge. The standard capacity for its magazine is 15 rounds.

Glock 23:
    Its a .40 S&W version of compact Glock 19, its dimensionally identical to Glock 19 however it is slightly heavier, because it uses modified slide, barrel and frame for .40 S&W bullet. It has standard capacity magazine of 13 rounds, however factory magazines of Glock 22 will also work with it.

Glock 24: 
    It is a competition variant of full sized Glock 22. Similar in concept as of Glock 17L. It has larger barrel compared to Glock 22, and has increased front weight to reduce muzzle rise even further. Additionally a compensator variant was also produced, designated as Glock 22C.
It also uses .40 S&W cartridges just as Glock 22.

 Glock 24

Glock 24c

Glock 25:
   Its a derivative of Glock 19 adopted for .380 ACP, with standard magazine capacity of 15 rounds.
Due to relatively low bolt thrust of .380 ACP, its design is quite different from other Glock variants. It has an unlocked breech, and operates via straight blowback of the slide. This method of operation requires modification of locking surfaces and redesigned locking block.

Glock 26:
   The Glock 26 is a 9mm Parabellum, sub-compact variant designed for concealed carry. It has smaller frame then Glock 19 and the pistol grip supports only 2 fingers, the 3rd finger is on the base of magazine, Shorter barrel and slide.
Its standard magazine supports only 10 rounds, but an increased base plate magazine is also available with 12 round capacity. 
All of the factory magazines of Glock 17 will also work with Glock 26.

Glock 27:
    It is a .40 S&W version of the Sub-compact Glock 26, with a standard magazine capacity of 9 rounds. How ever larger magazines of Glock 22 and Glock 23 can also work with it and can increase the round capacity up to 15 rounds.

Glock 28:
    Its a sub-compact version of blowback operated Glock 25.
It uses .380 ACP bullet, with magazine capacity of 10 rounds, but magazines of Glock 25 can also work with capacity of 15 rounds. 

Glock 29:
   Its a 10mm Auto equivalent of Glock 26. It features 96mm barrel and standard magazine capacity of 10 rounds. Like other Glock subcompact variants the Glock 29 the magazines of Glock 20 will also work in it, giving it 15 round capacity.

Glock 30:
    Its a .45 ACP variant of Sub-Compact Glock 29, with a standard magazine capacity of 10 rounds. The factory magazines of Glock 21 with capacity of 13 rounds will also function.
Glock 30SF is a short frame version, which reduces the trigger reach by 2.5mm.

SF (short frame) version

Glock 31:
   The Glock 31 is a .357 SIG variant of the full sized Glock 22, with standard magazine capacity of 15 rounds.

Glock 32:
    Its .357 SIG variant of compact Glock 23, with standard magazine capacity of 13 rounds. 

Glock 33:
    Its .357 SIG variant of Sub-compact Glock 27, with standard magazine capacity of 9 rounds.

Glock 34:
    It is a 9mm Parabellum competition of Glock 17. Compared to Glock 17, Glock 34 has 21mm longer barrel and slide. It has an extended magazine release, extended slide stop lever, 20 N trigger pull and adjustable sight. The top of the slide has a rectangular section milled out, creating a hole on the top of the slide, this is done to reduce front end weight of the barrel, for better balancing of the gun and to reduce the over all weight of the slide.

Glock 35:
   Its a .40 S&W variant of Glock 34, designed for competitions this gun has almost the same characteristics as the Glock 34.

Glock 36:
   Its a slimline version of Sub-compact Glock 30. It is chambered for .45 ACP. The Glock 36 is the first Glock pistol with single stack magazine design with 6 round capacity, and because of this Glock 36 can't use factory magazines of its larger relatives.

Glock 37: 
   Its a .45 GAP variant of Glock 17. It uses wider bevelled slide, larger slide, and different magazines but is other wise similar to Glock 17. The standard magazine capacity of Glock 37 is 10 rounds. 

Glock 38:
    The Glock 38 is a .45 GAP variant of compact Glock 19, with standard magazine capacity of 8 rounds.

Glock 39:
    The Glock 39 is a .45 GAP variant of sub-compact Glock 26, with standard magazine capacity of 6 rounds.