[Envisioning]

When Rick's group first met Gareth at Terminus and dropped their weapons, Rick dropped two handguns on the ground.

I thought he dropped a gun and a spare magazine in one scene, but I can't remember which? He left his revolver buried in the bag with the bow.

[Scoutmaster]

I’m fairly sure Rick dropped two semiautomatic handguns at Terminus. I need to watch the episode again (after steeling myself emotionally) to confirm that.

[Scoutmaster]

False alarm. I just watched "A" again.

Entering Terminus, Rick drops a 1911, then reaches behind his back and drops something else that is heavy and metal. The second object isn't shown. When the weapons are handed back, the scene is shot from Rick's right side. The 1911 is placed in Rick's right hand. The second object is placed in Rick's left hand, but the view of the second object is obstructed by Rick's body and right hand.

However, when Rick drops his weapons near the boxcar, he drops a 1911, then reaches behind his back and throws down an extra clip.

Ergo, the second item Rick dropped upon entering Terminus was the extra clip.