Home Forums Hunting & Shooting Hunting Optics toughest scope

They subtend an inch at 100 if I remember correctly.

The last one did the same thing this one did. Groups went and zero started walking a bit. I sent it in and they said it was bad but didn't say how. I'm going on a year waiting for a replacement. Two of the 3-9 SS I had that failed all the sudden wouldn't adjust more than a few mils one way on windage. I used a mirror to set center and then had plenty of adjustment one way and very little windage the other. I sent them in and they replaced them.

The 3-9 SS is a favorite so it bums me out to have a few more fail. Although nothing has survived the 7-08 fieldcraft yet. My first gen Ti in 30-06 munched a few scoped back in the day. I had better luck putting lighter scoped on it. Oddly enough the TI still wears a VX2 3-9 LR reticle. That it hasn't broke yet. It sent a few other heavier scoped to the grave.

Maybe mathman or someone could explain the physics behind lighter scopes holding up better. Something about them being easier to set in motion and not send their lenses forward maybe.

Bb

The overall weight of the scope isn't the factor. The mass of a particular internal part relative to the strength of its mooring is what counts.

"...so I really cranked them down."


Don't do THAT any more.

If scopes were slipping in the SS rings one thing to try would be scuffing the inside of the rings with some coarse abrasive paper.

I did scuff them and they are lapped first and then cleaned off good with rubbing alcohol. After the lapping and cleaning I scratched them a bit with a hex key after they slipped the first time. I'd set them somewhat light around 20 pounds initially. Obviously it wasn't enough so I tightened them up. I didn't go full gorilla on them but those scopes have a fairly heavy tube. I know a lot of manufacturers recommend like 18 pounds but I usually go tighter than that.

This last one shot great for a while being fairly tight and then went to crap. I've had some scopes that acted weird when too tight but I notice it right away. I don't think that's the issue here. The same inertia that makes them really want to slip forward I'm guessing is unseating a lense or something. I usually only go as tight as I can cranking on the short end of a hex key for leverage.

Bb

Thanks for the explanation.

I've actually explained the physics behind the opposite effect. Heavier scopes in reality hold up better (they add more weight to the rifle/scope system that accelerates as one system upon the rifle firing), all things being equal, since for a given force light objects accelerate faster, and that change in inertia is what is hard on things. The mass of the internal parts and the strength of their connections is a large factor, as well. In that case, the rifle system has a given acceleration and the heavier the internal part, the more force is applied to it to get it to accelerate at that rate.

This makes sense but also the heavier the internal parts, the more they resist acceleration due to a given force...right? I always get confused on these things.

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?

Thanks for the deatils details, Bb.

J

Yeah, sort of. The heavier the part, the more force it takes to get it to accelerate at a given rate.

To really explain it, we have to break it into two parts. First, consider the scope and rifle as a single object. A certain fixed amount of force gets applied to the rifle in the form of recoil. Well, I think it’s fairly intuitive for most here that the heavier the rifle, the less it accelerates due to that fixed amount of recoil. A heavier scope makes the rifle/scope object heavier, so it accelerates less under recoil.

Now, for the second part assume the rifle/scope is accelerating at a given fixed rate. For a heavy part to accelerate at the same rate as a light part, more force is applied to the heavy part. As mathman correctly pointed out, the strength of the fastening system of the part, relative to the force applied to the part, is what determines whether the fastening will let go or not.

So the factors that contribute to scope durability are overall heavy weight, and strong internal fastening systems relative to the weight of the internal parts.

A simple analogy would be someone driving a car. The engine (like the rifle’s recoil) has a fixed amount of power it can apply to accelerating the car with everything in it. If the car with its contents (rifle/scope system) weighs more, it’ll accelerate slower than if it weighs less. Now take one particular item in the car (like an internal scope part). The car and its contents accelerate at a given rate, and if that one item inside is heavy, let’s say it’s the driver, then the seat will have to apply more force to accelerate the driver at that given rate than if the driver was lighter. And if the strength of the seat is insufficient compared to the weight of the driver, the seat will collapse and the driver will break loose inside the car (like an internal part breaking loose inside the scope).

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.

The fastening of the internal parts, relative to their weight, must be fairly exceptional.

Thanks. I get the internal scope part analogy and certainly understand that the momentum of said parts can cause issues under recoil, but I am not a physics person...it seems that with a given force, a heavier scope (or scope parts) would both accelerate and also resist that acceleration more.

People say a heavier rifle soaks up recoil more than a lighter rifle...and thus kicks less. I see the same logic confliction here as a heavier rifle (assuming enough recoil is there to get it moving) would both kick more due to more momentum and also resist that momentum more, and thus kick less.

I dunno......

Heavy objects have more inertia than light objects, which means they resist changes in momentum. Force is equal to the rate at which momentum changes in time. So for a given force, the light and heavy rifles will both gain the same amount of momentum in a given period of time, but the lighter rifle will accelerate faster to gain that momentum. If the rifle/scope is accelerating faster, then there is more force applied to the internal parts and fastening systems.

Nightforce

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.

unertl.

Thanks for your comments, John.

The “single anecdote” thing wasn’t meant as a slight or jab. You asked how that single example fit with the physical concept, and my intention was just to point out that a counter example doesn’t disprove a principle when there are other confounding variables involved.

So you're still essentially saying that many, many examples of light scopes retaining zero for hundreds or even thousands of rounds is contrary to your understanding of physics?

I don’t believe that’s what he said.

He said all things being equal, lighter weight as a “unit” is harder on a scope than a heavier “unit”…and by unit I mean rifle/scope combo.

“All things being equal” not including variables like erector springs and the like, which likely explains Phil’s situation (and many others of course).

Simple enough to understand even for a naive like me.

Dave