I recently purchased, and mounted the Holosun 510C red dot on my SP5. I took it out to the range today to zero it in. I started at 15 yds to see if I can hit paper, and if so where on the paper? I finally got it somewhat zeroed at 15 yds, then went out to 25 yds to zero it in. I got it where I wanted, then brought it back to 15 yds to have fun (pictured below).
Went back out to 25 yds for more fun, and realized I was starting to show a little fatigue. Regardless of a little fatigue, I was still happy with my shooting at 25 yds (pictured below). All in all, I'm loving this firearm and my current setup!