Yes, you can safely fire 7.62 NATO rounds through the Henry Single Shot chambered in .308 Winchester.
Here is the breakdown of why this is safe, along with a few considerations:
Safety: It is generally safe to shoot 7.62x51mm NATO ammunition in a rifle chambered for .308 Winchester, as the .308 is typically loaded to higher pressures than the 7.62 NATO.
The Reverse is Risky: While 7.62 NATO works in a .308, you should avoid shooting high-pressure .308 Winchester ammo in rifles specifically chambered for 7.62 NATO, as that can be unsafe.

Good evening to you!! The 7.62 NATO is interchangeable in 308 rifles. So shooting 7.62 NATO in your Henry single shot 308 will be fine. Hope this helps. Have a good rest of your day.
🇺🇸🇺🇸 'Merica' 🇺🇸🇺🇸

Yes, 💯‼️

Yes.

Hi David, yes, you can fire 7.62 NATO in a .308 rifle, as the .308 is designed to handle the lower pressure of the 7.62 NATO round. However, the reverse is not always safe due to differences in chamber pressure and headspace tolerances.
Stay safe & have a great day!

Hi David and welcome. Yes you can. 7.62 NATO is a slightly lower pressure round than the .308 Winchester. It is the opposite for 5.56 and .223 with 5.56 being the higher-pressure round. 7.62 NATO will fire just fine. Cheers, stay safe and enjoy!