Baz or Gary C would be the best to answer this.
As far as I know they are rated upto .50 BMG.
Someone had an issue with one of of mine I was selling, but try as I might I could not get it to do it for me (and I knocked hell out of the scope to try...I was a lot nastier than a .223).
I recently put the same scope on a spring gun and drove it round the box and it was fine.
It did hang once in a while going R-L but I put this down to the fact it had spent 5 years or so on a PCP and may have been slightly entrenched.
Very good scopes, particularly for the money. All of my rifles have MTC on them, and the above mentioned Viper will be going on a .308 so I can learn how to dial in and gauge the wind as I want to take up F/TR later.....provided I get an FAC...dont see why not though