I hate to say it, but if he's lost 6 deer to Rocket Ultimate Steel heads with little to no penetration there's another issue other than the choice of broadhead. I don't particularly care for the blade retention on the Ultimate Steel, but the tip is sharp and the blades are scary sharp. They penetrate well.
How well is his bow tuned?1 deer can be a mistake, 2 deer could be a coincidence.........6 deer is a serious problem and I wouldn't look 1st at the broadhead.[:-]
I'm sorry but I don't buy 6 deer hit perfectly and all 6 lost due to broadhead. It doesn't work that way with ANY head.