I purchased a bunch of these [paving stones](http://www.lowes.com/ProductDisplay?partNumber=12200-215-110601999) in order to make a fire pit. I laid out the fire pit and it worked okay, except if you'll notice on the description of the stones it says "Back lip assists with alignment for easy installation". Well, I guess the back lip may be helpful for certain situations, but it only seemed to hinder my efforts to lay these stones out in a circle with three layers of stones. The back lip is about an inch at the back bottom of the stone that is raised out about a half inch from the rest of the surface.

![enter image description here](https://i.stack.imgur.com/JV9dt.jpg)

*The paving stones in question*

Am I using the lip incorrectly? Is there a way to lay these stones out in a circle where the lip actually helps? Or, what is the best way to get rid of these lips (I have 27 stones total). I tried to chip away at one of them with the back of a hammer and while it did work, it took a ton of effort and time.