That whole scene was set up nice. You had an old fashioned wild west saloon standoff.
You got the one guy talking about getting the gun off a cop with a smirk. When rick says he is a cop they guy says well it was a dead cop. But you could tell he was kind of bragging about it. No other use to bring up where he got the gun. I think Rick probably feels that the guy killed the cop before taking the gun.
The fat guy peeing in the saloon was basically another alpha male move to show he can mark his territory. We also got the fat guy making the comment of not having any action and hoping to get some if he went to the farm but apologizes after saying it.
Another thing that I noticed after it all went down is the bad guy wearing a shark on his shirt...intentionally symbolism or not?
Rick's cop sense took over and he knew the guys were bad when they kept pressing the issue. And we have to remember that the guy went for the gun first so rick took them out.
I think Rick, and the others, sensed these guys are a group that was not trying to join a group to help, they would want to join the group to take everything the group had and move on.
I liked that whole scene.