As for the 1887 shotgun, that gun is lame as hell. Its way over powered and the range is too ridiculous to believe for a shotgun.
actually, it's one of the few "realistic" shotguns found in gaming IMO.
It's a 10 gauge who's real effective range would be about 50 yards with buckshot. With FMJ, aka a jacketed slug, it would be closer to 75/100 yards. In the game they gimped it down to about 20 yards... oh well.
The rest of the shotguns in the game use the puny 12ga
It's also the same shotgun that arnold used in T2.
10ga on the left, puny 12ga on the right
for some reason, video games perpetuate the myth that a shotgun has a 3' spread pattern 5' away from the end of the barrel, and is only effective out to ~10 feet.
read up on shotgun spread patterns
http://www.theboxotruth.com/docs/bot20.htm
But then again, this is the same game that claims the m16 is more powerful than the m4, and claims the acr with it's 6.8spc round is only "on par" with the 556 powered m4. Or my favorite, that 44 mag / 50AE rounds are more powerful than rifle rounds as they take less rounds to kill.