Because there are perfectly capable scoped weapons out there that don't have a 5x critical multiplier. Hunting Rifle, Trail Carbine and AMR springs to mind here with the first two able to one-shot kill full grown deathclaws with precise shot placement.

Also, sneak attacks are 100% guaranteed even when using a weapon with a 0x critical chance multiplier. The first round sent downrange should be the killing round.

because you don't need it to be 10 for reaching 100%
lck 8 -> 8%, built to destroy 3% -> 11%, finesse 5% -> 16%, 1st recon beret 5% -> 21% -> 105% crit chance

@kor'ah

true that, but if you get discovered, you'll still do criticals all the time. saved my butt more than once...

Not being discovered is incentive for improving your play. It is a good idea to keep a Riot Shotgun with bean bag rounds and slugs handy. Just in case things do go south.

Thanks people. great help.

i will start playing later today.

Actually, if I understand it correctly, critical chance and sneak attack criticals are seperate things.

Critical chance is the chance you will do a certain amount of bonus damage, depending on the weapon, which isn't displayed in the guns description in game (check out the Fallout Wikia site for more details). Most weapon's critical damage is the same as the weapon's base damage so you'll do double damage but there are some exceptions. The Anti-Material Rfile does 110 base dmage (fully repaired/100 Guns skill) but only does 80 extra damage on a critical hit. The Abilene Kid LE BB rifle does 4 damage and 70 critical damage.

The Sneak Attack Critical then takes the combined damage from the base damage and any critical damage and mulltiplies it by two. This means a weapon with a x0 Critical Chance Multiplier will still get a boost to it's base damage but misses out on the critical chance damage bonus.

For example the Sniper Rifle will do 62 base and 62 critical damage for 124. Add a sneak attack critical and it becomes 248 damage. A Sawed off Shot gun with a theoretical 100 base damage and 0 chance for a critcal bonus will only do 200 damage on a sneak attack critical.

I have done a sniper/melee guy, but here is what I set things to:

Strength = 5 (you can take the implant and be able to handle most weapons - except anti-material rifle, which is a bit overpowered imo)
Perception = 6 (perception is a stat you could bring down one or two points if need be, but i think it is good rp wise to have a decent perception stat )
Endurance = 6/7 (gives you a good amount of health and implant options)
Charisma = 4+ (Someone else pointed out not having charisma lower than 4, i completely agree - especially if you want a competent companion)
Intelligence = 6 (I would venture to say you could put this at 5, but then you get those half points, might as well pull it up to 6)
Agility = 6 (Agility is fairly important as NV has added some additional effects to the stat - definitely 6 or higher)
Luck = 6/7 (Mainly for critical chance and gambling, but still nice to have a decent luck stat)

Traits =

1. Trigger Discipline (don't know what that one poster was thinking, this is the best trait available - big accuracy boost and the shooting speed is barely noticeable)
2. Up to you, but I'd suggest "Small Frame"

Tag =

1. Guns
2. Speech (pretty important in game)
3. Repair

I would build up your guns stat slowly along with speech and repair...these three stats lead to some of the better perks, or are just useful in game.

i got that perk at the beginnin where you shoot 20% slower and 20% more accurate. i hit stuff with a high accuracy that you cant even click on in vats because its so far away. high perception (improves acc), agility, some strength to handle sniper rifles, guns, sneak, and the weapon handling perk all help.....