It does, in fact, have a safety, but it's quite hard to engage. But this is not a complaint one would ever voice in the Red Army. Your officer would reply, "Safety? Safety? Is gun! Meant to kill! No warrior should know he has safety on gun, because he should be killing enemies of homeland! Safety make loud click to aid enemy in locating warriors! No safety!" while pounding his fist on the table.
And the Mosin can kill enemies of homeland. The muzzle blast will vaporize green growth within a few feet of the muzzle, and even if you miss, the enemy will be reduced to shouting "WHAT?" to communicate.