Lead sled isn't a guarantee of utmost accuracy either. I shoot far better off of a front rest and sandbag than I ever did out of a sled, heck, better off of a bipod prone than I do out of a sled.

I'm surprised to hear you can't find a factory load that doesn't group better than 2-3" at 100yrds. Are you possibly running bullet weights not appropriate for your twist and velocity? Might have some warranty level issue if everything is lined up and you can't get it any better than that.