Try Insurgency: Sandstorm. It's a completely different style of gameplay, but in addition to properly simulating a chamber, it also properly simulates magazines

Try Insurgency: Sandstorm. It's a completely different style of gameplay, but in addition to properly simulating a chamber, it also properly simulates magazines. Reloading retains a used magazine rather than dumping the ammo back into a fungible pool. Double tapping the reload key allows for dropping the mag for a slightly faster reload. Once you've cycled through your supply of fresh mags, loading a used mag leaves you with the same number of rounds as when you discarded it.