Best barrel length for NF 1-8 ATACR?

[BallisticHarmony]

I’m looking for the shortest barrel length possible while still being capable at ranges that require the 8x end. Essentially I want to fully utilize the magnification range of the optic while keeping the rifle as compact as I can.

How far can one reasonably hit a 12” target with a 77-gr bullet and 8x magnification?

I’m stuck between 14.5, 16 and 18. Also thinking about pairing the ATACR with the Scalaraworks LEAP/Scope and Magpul bipod. Any thoughts on that are appreciated as well.

[markm]

You can do 14.5 with 77s. With a good spot, we aim to punch the 7" flapper at 750 yards using good 77 gr handloads. For 1000 yards, you're working to hit that 12", especially if there's wind/variable winds.

[crosseyedshooter]

You can check with a ballistic calculator but you'll need the muzzle velocity with your different barrels. For my case, I think Magtech 77gr is transonic around 750 yards out of a 20" barrel. I could probably make it to 650 yards with a 14.5". It'll be roughly 6 mils drop while the ATACR reticle has up to 10 mils, almost as if they had a bigger cartridge in mind.

This is just purely academic looking at ballistic range and not considering wind drift or effective bullet energy.

Here's what a 12" target might look like at 700 yards with the ATACR reticle:

[BallisticHarmony]

That’s very helpful, thanks. Seems like based off that, maybe the ATACR is overkill for the supersonic range of 5.56...? Maybe the NX8 would be a lighter, more realistic option...?

[BallisticHarmony]

Upon further examination, the NX8 has 10 Mils of drop as well.... Seems like overkill, but I still want the best LPVO for my carbine. Since the ATACR has better glass I’ll probably still go with that.

[crosseyedshooter]

I think choosing a barrel to maximize the use of drops on the optic reticle is probably backwards anyway. It makes more sense to choose barrel and optic based on intended use cases. Target shooting to maximum distance vs effective man-stopping or hunting or indoor home-defense all have different and sometimes competing criteria.

[markm]

For what it's worth, trans-sonic has not been an issue AT ALL for us with 77 gr SMKs. The ONLY time that has shown to be problematic is out of my 20" 1/12 .308 combined with 168 gr SMKs. I really saw fanning.

77s in a 1/8 or 1/7??? No sweat beyond super sonic ranges... at least at our altitude.

[BallisticHarmony]

For what it's worth, trans-sonic has not been an issue AT ALL for us with 77 gr SMKs. The ONLY time that has shown to be problematic is out of my 20" 1/12 .308 combined with 168 gr SMKs. I really saw fanning.

77s in a 1/8 or 1/7??? No sweat beyond super sonic ranges... at least at our altitude.

So you don’t think it’s necessary to go any longer than 14.5” for most 5.56 engagement distances if using SMK/TMK? What about 70 TSX?

[Stickman]

So you don’t think it’s necessary to go any longer than 14.5” for most 5.56 engagement distances if using SMK/TMK? What about 70 TSX?

Engaging what, or whom? What distances are you looking at using the weapon? Markm shooting on his 1k KD backyard range is awesome, but if you can’t shoot farther than 200 yards around your locale than it is a moot point.

Hopefully that makes sense. You may find yourself with the wrong optic if distance is your primary focus, especially if it end up being unrealistic.

[markm]

Engaging what, or whom? What distances are you looking at using the weapon? Markm shooting on his 1k KD backyard range is awesome, but if you can’t shoot farther than 200 yards around your locale than it is a moot point.

Exactly. The original parameter was to ding a 12" plate. That said... at our elevation, 14.5 with cut it with ease. As far as TSX, I will never shoot that nonsense, so I'll leave that to the Texas Hog hunters to address.