So why has the 6.5-ounce 2.5x Leupold M8 that's been on Phil Shoemaker's relatively lightweight .458 Winchester Magnum managed to retain zero for decades now?
Well, as with most things, a single anecdote doesn’t prove a concept, but I would say that the scope in question has retained zero despite being lightweight, not because of it. I think you would agree that a 7 lbs rifle/scope combo is harder on the scope than a 9 lbs rifle/scope combo. On
The fastening of the internal parts, relative to their weight, must be fairly exceptional.
Jordan, I have far more than "a single anecdote" about lightweight scopes (especially Leupold fixed-powers) that have retained zero for years in harder-kicking rifles. I suspect the reason is that Leupold's internal parts during the era when they made very tough M8s is that they used adjustment springs far heavier than required for the very light erector tube.
Also have "anecdotes" about other brands of lightweight, fixed-power scopes that also retained zero on hard-kicking rifles. Among them was the early 2.5x Bushnell that one of the first PHs I hunted with in Africa had had on his .458 Winchester since the early 1950s. His initial experience was with culling many, many of Cape buffalo on ranches in what was then Rhodesia. Afterward he transitioned to a PH for safari hunting, and had done that for many years when I hunted with him and his son in South Africa in 1992. The same Bushnell was still working fine on the same .458.
Dunno if you know the background of Bushnell scopes. The company was started by Dave Bushnell, who spent some time in Japan during his military service. He eventually asked a Japanese optics company if they could make scopes like of the post-WWII El Paso Weavers (which also had a reputation of being very recoil-resistant), and they said yes. They worked very well, including retaining zero under repeated heavy recoil. Of course, the Bushnell "company" continued on long after Dave Bushnell was gone, just as "Weaver" did. But the toughest scopes from both companies were VERY tough, despite being light.
