I recently found a Hunting rifle finally. But I'm still using my Varmint Rifle. Big reason is that while I did manage to get a scope for my hunting rifle, it doesn't have a silencer, so the Varmint still wins out for my playstyle. Now, some enemies require a little more oomph, so I'll whip out either the hunting rifle or Cowboy Repeater depending on range. That Gun is the only unique weapon I've found so far though.
I have to admit I actually impressed myself yesterday with the Varmint Rifle. I have ED-E, so I get the compass markers way before I can see a foe. I was on the top of a cliff face around the Goodsprings Source area, and looked in the direction of the marker and peered down my scope (night scope, and it was dark out). I barely could make out a Gecko in the distance, lined up my sights, waited for just the right moment, and squeezed off the shot. I didn't think I'd hit, but as the shot went off it went into slow-mo and followed the bullet for 4 or 5 seconds of flight before impacting the gecko's head.
For a low end rifle, it's still pretty useful