ATN 4K Which should I buy?

I have owned the ATN 4K PRO 3-14x and now the 5-20x. I'd skip the Buckhunter unless you just plan on using it in daytime only. The PRO gives you day and night use via included IR light. Scope rings are included.

I'd recommend the 5-20x for any shooting past 30 yards because the "zoom" on these scopes is digital, not optical. So the 3-14x scope has a 3x optical zoom and 14x digital zoom. The 5-20x scope has a 5x optical zoom and 20x digital zoom.

The 3-14x is good for those shooters hunting hogs and coyotes where they need to scan a large area quickly. I found the 3-14x to be subpar for any sort of accurate shooting past 30 yards when it comes to airguns and the small holes they create on paper because I had to always zoom in up to the max to get any sort of good accuracy, and the image quality wasn't that great at full zoom.

The 5-20x is more suitable for airgun work because it's already zoomed in more and even at 20x it gives you a slight advantage when trying to shoot accurate groups.

That being said, I tried to shoot at a large white steel gong (12" metal gong) at 60 yards with my 25 cal Crown, fully zoomed in, and it was very hard to see the groups I was printing at that distance.

That being said, these scopes are good for larger calibers where trajectories are flat using powder burners and precision shooting is less of a requirement.
 
I think this scope is perfect, but for the right context. If you're punching paper... probably not the scope for you. If you're doing pest control 10-50 yards... perfect... if you want to record said pest control... there is nothing better IMO. 

The way to deal with the small reticle is to setup profiles. Zero at 20, 40, 60 and you'll never have an issue. I can range, and change profiles just as fast as someone can spin a turret. I use the profiles for range as well as different pellets as well. ATN will support airgun needs at some point. We've made big steps in that regard... the right people are actively engaged.

You're getting a quality day scope, night scope, and camera all in one. Hard to beat.

This is the one I have... https://amzn.to/2zHtRIM 

t
 
I believe something like this (see link below) would allow you to download the firmware from your ipad to an SD card (with the micro SD card inside it) adapter to allow you to flash the scope.

https://www.amazon.com/dp/B07J4ZCTZK/ref=cm_sw_em_r_mt_dp_U__DOq9Bb4RBJF78

not an endorsement, just throwing out a suggestion...

any number of lightning connector to SD cards adapters are available.

By the way, I also have the ATN 4k Pro 5-24 on my Vulcan Tactical and while at first I had my doubts about this scope, mainly with the digital zoom, but once I started playing with the tech I was happy with purchase. Specifically the digital zeroing of the scope had me floored... It was so easy and quick. 

I'm sure at some point more reticle options will become available, it'll be in a firmware update. I just wish there was more zoom.
 
I see they sell them for tactical lights. But I'm wondering about the size I would need?

Think with Bore lights a lot has to do with battery size, I have 2 bore lights and they both have different cap sizes, ones AAA and the other is AA batteries, see what thread size you need and then go to a place like cabelas, bass pros and look at what they have on the shelf.