I'm looking at getting a Holosun 407CO with the 8 MOA ring reticle, does anybody have experience with it? pros or cons? it's going to be mainly for shooting carry optics. I'm also going to get the EGW rear sight dovetail mount first before investing in milling the slide of my 320.
thanks

It will work for what you describe. However you will want the biggest window you can get if you like shooting it competitively. That would mean going with an SRO, Delta Point, or the huge Sig Romeo whatever.
I started with that sight and changed to a SRO. Much easier to keep the dot on the screen at all times.

The big ring is too busy for me. I love it on an AR and I like it for shooting steel but I found myself shooting too soon before the sight settled back to where I wanted the bullet to go when mounted on my M&P. 2.5 MOA SRO does not give me that issue.