Fuel line flair

I'm getting ready to flare my niccop fuel lines, it's been awhile but I have done a fair amount of steel lines. I borrowed an OEM brand flair tool and practice on some old steel line. On my old flair tool I could tighten it all the way then flair and it always worked well. But this one really seems to crush the line and leave a lot of imprint, if I back off it doesn't hold during flairing.