It's 'supposed' to be stiff.
That's so it holds a fully-loaded magazine securely for a soldier's weapon as he runs, jumps, crawls, makes parachute landings, kicks in doors, and any other highly physical activity that a combat soldier engages in, because if it retains the magazine, the soldier still has a viable sidearm to depend on until he can find an undamaged long gun.
It was designed to be a weapon - not for comfort in a game.
That said - lube it, as has been suggested - it might help - but what 'will' help will be more range practice, and more dry-firing time - getting used to 'that' piece in 'your' shooting hand.
Scouts Out!