Ok so I've seen people say that for a sniper build they put their critical hit chance high but I've also heard that if you make a sneak attack its an automatic critical hit. I was wanting to know if anybody knows how this works and if the perks and stats to help raise critical hit percentage are relevant with a sniper build.

Also with DT if an enemy is wearing armor of 10 DT but their head is unprotected is the DT still in effect.

Thanks for the help.

An undetected sneak hit is always a critical hit, raising critical percentage through stats and perks is very relevant to a sniper build - you can achieve 100% critical hit with a sniper rifle and DT counts across the whole body, regardless of where you hit them. Though headshots do extra damage.

Hope I got that all right

If your realy going for the one shot one kill method then no luck isnt that important as the sneak attack will in fact always crit.. however if you do a sneak attack and someone else and thier 5 friends notices.. you may wish to be lucky.

There is critical hit -which adds critical damage on top of normal damage weapon does. Critical damage is usually same as normal damage so critical hit doubles damage. Shotguns have low critical damage however.

Then there is "sneak" critical hit which doubles critical damage and add normal damage so result is usually triple damage. Means its more destructive than normal critical. Sneak critical is one which is done while you are hidden from enemy. Sneak critical is done automatically (100%) when you sneak hit something.

For critical damage of individual weapons look at Fallout wiki.