It is an American made pump-action shotgun and a simplified version of the Mossberg 500 shotgun. The variant used in all STALKER games is the Mossberg 88 6-Shot Security and uses a pistol grip with an all synthetic finish. The Chaser 13 is particularly invaluable as a CQB weapon due to it's compact design and universality. It uses 12x70 shot shells and 12x76 Slug and Dart rounds.
The Chaser is the lightest combat shotgun available, with it's high close range damage, cheap upgrades, light weight and very high durability, it becomes one of the more economical back-up CQC weapons the player can carry.
Professor Sakharov will sell them after you accompany Professor Kruglov in taking the measurements for the Psy-Helmet. Pavlik, Chef, Snitch, and Lukash's expert bodyguards are the only stalkers armed with Chaser 13 shotguns, making it exclusive to the Freedom Faction. The tube magazine holds up to 5 rounds, with one round chambered (5+1 configuration). It weighs 3.0 kg unloaded.
In Clear Sky, the Chaser 13 is widespread and commonly employed by experienced members of most factions , and can be upgraded by most technicians, although it has very low stopping power compared to the other games. It is also found on several Zombified Stalkers in Yantar. It's barrel can be threaded to allow better accuracy with Slug and Dart rounds although this forgoes its ability to fire Shot shells. It's a very reliable weapon and still, extremely effective at close range while can be effective on medium and against heavy armored targets using Slug and Dart rounds. The weapon can be upgraded to hold up to 8 shells.
One weapon of this type is located in stash in Swamps near the pump station, the coordinates of which can be bought from either Cold or Nimble for 1500 RU. The Chaser 13 is a very valuable weapon at the start of the game, given the lack of automatic weapons and the abundance of shotgun ammo. Note however that the area around the stash is slightly radioactive.
This weapon can be acquired in the beginning of the game. Many Loners and Bandits carry it, and it can be purchased from Owl. It now has a 7 round capacity (9 after upgrade), and can be upgraded to semi-automatic. However a SPAS-12 can also be found in the beginning of the game, which is definitely a superior shotgun, sporting a semi-automatic firing mode by default and better stats.
However, it still has some advantages over the SPAS – weighing lighter, but still packing almost as much punch – along with its tighter grouping of shots, a more methodical shotgun user might be able to get more out of its 50 damage per shell than they would with the more rapid-fire SPAS.
Trapper, a mutant hunter can also give you his custom Chaser 13 named: Predator, after completing his list of mutant hunting related jobs.
Combat shotguns like the Chaser 13 and SPAS-12 can chamber different types of shells simultaneously, for example a Chaser 13 could be loaded with 4 shot shells, 2 Slug rounds and 2 Dart rounds. This is done by pressing the fire key during reloading and causing the player to stop reloading. Once satisfied with initial load, pressing the "Change ammo type" key ("Y" key by default) will have the player chamber new shells once he resumes realoding. This method allows one to adapt to different situations quickly as one can rapidly switch from unarmored hunting to armor puncher in a moment's notice. Since you can't choose which shells to use after loading, it is best if you load 1 slug, 1 shot, 1 slug, etc. so you can be flexible.
The Maverick model 88 is commonly mistaken for the Winchester 1300, although on the receiver of the model 88 it has the words "Mossberg model 88" printed on it. This is commonly visible if the game's: texture, object, and anti-alias levels are set near half the bar.
It should also be noted that in the game files, its scripts refer to it as the wpn_wincheaster1300. It is odd that the developers chose to use the Mossberg 88 as a mirror while using the Winchester 1300 as a script name.
In Shadow of Chernobyl, the Mossberg 88's viewmodel is aimed slightly above the crosshair.
The Chaser 13's model graphic changed in Clear Sky and Call of Pripyat. The Chaser 13's receiver is now painted dull black, while during Shadow of Chernobyl, the weapon's receiver was painted light gray.
This shotgun is described as having "all its details coated with a weather-resistant finish" which, as per standard on a Maverick 88 Cruiser/Persuader, would be a Parkerized finish (which actually does have a matte gray look).