All you need is critical chance, and if you're going to crippling, then better take Finesse trait, because 10LK+x3More Critical=only 25%, not enough for arms/legs, even my 31% isn't good, because I have only 6LK.
All victim need is high endurance and, probably, luck.
So, you'll often cripple people with low EN, and it'll be a problem vs high EN. You need better 35% critical chance to just get critical hit, and better critical perk, of couse, to increase chance of possibility to cripple.
Also use one-handed weapons for this.
Best choice is EW: laser pistol - tier0 weapon, easy to craft, 4 AP shot, 5 AP at hand, 4 AP with BRoF, 35 range.
If you're SG, then use whatever you want from mauser to P90C(the best choice 'cause of 30 range, but... it's P90C...). Desert eagle has 25 range, I usually use this. Also BB gun funny thing, but it has 22 range and 5 AP to shoot.