273 Commando ignition wire question

I'm having the opposite problem with the white spark plug wire grommets for my '65 Barracuda FS 273. I have two new sets here, one from Mega Parts, and the second set from Classic Industries, they appear to be identical, and from the same manufacturer. I am installing new, original style 7 mm plug wires, and the grommets are too lose. They won't stay in the recesses of the valve cover holders, and they slide on the wire once snapped shut. The few originals I have left fit tight. Anyone else run into this issue?