Every series of shots, after about 3 or 4 rounds the front sight hood comes off my M70 .458 Win Mag from recoil.

What is the best way to hold it on better so it won't?

NECG makes sights which have a small detent which must be depressed to remove the hood. That said, I don't like shooting with the hood on, therefore I only use a hood to protect the sights while in the case then remove them when the gun is to be used.

Geronimo

As Geronomo said I believe that the sight hood is for the protection of the front sight during transportation. I always remove them before shooting.

With 350g or 400g loads mine stays on! With 500g I put it in my pocket

Thanks- sounds like it's pretty normal then.