I can't imagine a place where sniper rifle wouldn't raise any suspicions other than the battlefield. Sure, there can be hives run by gangs armed with semi-auto guns, shotguns and so on. But a sniper rifle? There's only one purpoise this weapon has and only the soldiers are allowed to have it in the Imperium.
Matter of interpretation... One man's "sniper" rifle is another's hunting rifle to shoot animals with. And in GW's Necromunda, the gangs roll around with heavy bolters and plasma guns.