There's no danger of being shot at this site despite what you may read, been up there loads of times and the only unnerving thing is the low flying military aircraft that sometimes buzz the site, don't worry they won't bomb you.
Never found it since!!...wound me up writing that. So today I made sure I chuffin' well found it again.
Easy to miss and not a deal there when you find it, it has to be said. The kerb/rubble bank although overgrown is very wide with some good coarses of stones visible in the heather.
The site is marked as being in a 'Danger Area' on the O.S maps (rifle range), so keep your head down if there's red flags about.
I was once taken up here years ago. There wasn't much to see, a low rubble bank and stones that may or may not have had something to do with the circle, and it was very overgrown.
Never found it since......