I'm not disputing what the others are saying about this at all. Lots of people have said the same things, often from bad experiences, and I don't doubt them. Just my personal experience is that I have never had to do more than tighten the nut with about as much force as I can muster. I'm not a particularly strong guy, but I give it what I've got. I often use plastic spinners, even on four strokes up to 50 size. I have an aluminum spinner on my OS 70 FS. I was going to try a plastic spinner on that one too, but when I tightened the nut the plastic distorted, so I bought a metal spinner. Plastic spinners differ, some are tougher than others, which may account for the various experiences. My Dubro on a Saito 50 has never failed me.

I tighten nuts with a Robart wrench, and spinner nuts with a rod through the hole when there is one, or an adjustable wrench if the Robart won't fit over the nut. The Robart works for all stock prop nuts, metric or English.

The one thing that has kicked off a prop recently is when I was trying to start an unfamiliar engine. I was amazed when it kicked off the prop twice in a row, even though I had put it on tight the way I always do. That's when tried the chicken stick and got a hard bump. It was not actually hydro-locked, but it was flooded and inclined to kick back (OS 46AX). I've run a lot of Enyas and they like to be very wet, but some other engines do not. This is one that doesn't. Once I cleared the flood, the prop stayed on and I started the engine.

Jim