IMHO stay away from the Nikon P-300. The glass is good but it is large and the reticle is awful.
I ended up saving up a little more and getting the Hilux CMR4-762AK for around $400. It is super clear glass, great features like locking/covered turrets, 30mm tube, and the reticle (while seemingly busy at first) is very well done with a ton of information on it. It also works with the 300blk out quite a ways for the BDC and since it has normal MIL lines as well it can be adapted if necessary.
The only problem I have with it really is the eye box is relatively small.
The illumination is not daylight visible, but the reticle is designed pretty well for daylight close-up engagement.
It is not long, but it is also not light. I usually run micro red dots, though, so take that FWIW.
Edit: wrong P/N for optic