To cluck on a pot and peg call, you want to pull the striker in a very short stroke with pressure on the call surface. You want a single note to "pop". It should be sharp and quick. The striker should not leave the surface of the call. Increasing or decreasing pressure, and how you hold the callwill adjust volume accordingly.

To purr, you want to drag the striker across the call with very light pressure to create a vibration. Again, you can control the volume by how you place the call in your hand.

I haven't been impressed with any of the major turkey call manufacturer's box calls. I feel the same way with most pot and peg calls. IMO...find a custom call maker. They usually spend a little more time tuning their calls and have a much better sound.