Didn't fit, too big - Real Avid AR10 Lug-Lok Upper Vise Block

I have the AR15 version; it is fantastic and works brilliantly. For my AR10 build, I waffled to spend the money for this tool (for just 1 use). I regret doing so. When placing it on my Wilson Combat 308 barrel, it didn't fit. The teeth at the end had too large a circumference and it would only fit halfway in the breech. So, I think that I now have to file it down to decrease the circumference. I usually love Real-Avid products, but regret this one.