What does sniper on gun profile mean 40k?

Answer 1

"Sniper" means that the gun is Strength 3 but you require a 4+ to wound reguardless of the targets toughness, the weapon causes pinning checks if an unsaved wound is inflicted, and the weapon gains "rending" on a roll of 6 when wounding.

VS Creature = Roll to hit, then roll a 4+ to wound, if a 6 is rolled then the shot becomes AP 2, then check for pinning.

Vs Vehicle = roll to hit, then roll for armor-pen, if a 6 is rolled then you roll an extra d3 and add 1 to the damage chart for being AP2

(Str 3+6+3= Glances armor 12, +1 to damage chart)

Sniper rifles can take out light vehicles. Dont forget!