I ran a pretty rough poolroom for 7 years so I can go on with war stories for days. The place averaged a couple of fights a week and about once a month someone would pull a knife or a gun.
Problem was after barring someone for fighting, they would go whine and cry to the owner and he would let them back in. I always figured he did this because he hated to see a dime walk out the door and he was never in the line of fire when the crap started.
Here's one mild story-----My girlfriend is tending bar and I happen to be looking in her direction. A guy is sitting at the bar and he motions her over. He leans forward over the bar like he is going to whisper something to her so she leans forward and he pinches her boob. I take off around the bar and before I can get there, she leans forward and motions him to do the same. "What the hell is she doing?", flashed through my mind. As soon as he leans, she nails him with a roundhouse right in the mouth. His head snapped back and over he went out of a high barstool flat on his back. OUT COLD!!!
The tough part for me was after she hit him, she came flying out from behind the bar, spitting venom and wanting to REALLY work him over. I had to put her in a bearhug and carry her off!
We picked him up, carried him out back and threw him in the dumpster. Went out and looked about an hour later, he was gone.
5' 1" tall, 120 lbs., toughest gal I ever met. From then on, I always made it a point to stay on her good side!