Last night, I put the LumaForce light and the L&M Single Ring mount through the paces. After installing the mount and light, it's rock solid. You can't twist or move either with your hand. I shot 25 3" magnum slugs/buckshot without so much as a hiccup. Shoulder's a little tender though.
I'm very happy with my $75 investment and highly recommend this combo.
Thanks again jb1911 for recommending the L&M mount.
Glad to help. I don't know why more people don't use this mount.