Thread: Scope rings - Steel vs Aluminium

Steel has 3 times the density of Aluminium. That means, for the same volume/physical size, steel weighs 3 times more than aluminium and is stronger than aluminium (but not 3 times stronger). On the other hand, for the same weight, aluminium will be 3 times bigger than the steel, is about 40% stronger than steel.

Now, to achieve the same strength you will need steel that is about 40% heavier, and 60% smaller in size compared to aluminium. The weight difference is why most modern mid-ranged bicycles use aluminium for its frame instead of steel.

Steel has two mechanical advantages over aluminium - it is wear resistant and it is fatigue resistant. these two advantages means we use steel to make rifle barrels and knifes and swords. Also for bikes where fatigue resistance is important - for example park BMX - steel is used over aluminium.

But these two advantages has no application to rifle scopes rings. I have never seen or heard a scope ring breaking in half due to fatigue caused by repeated recoil. In fact, I would have thought if there is recoil induced fatigue, the scope would probably die before the ring dies. Yet as far as I know all scopes, cheap or expensive, use aluminium for the body. No one uses steel. So obviously everyone thinks that the thin aluminium tube is strong enough to withstand recoil for a life time (for those scopes with life time warranty).

As far as I can see, we only need these characters from rifle scope rings:
1. that it is strong.
2. that it is light.
3. that it is made with precision.

It would seem to me that Steel offers no advantage whatsoever. For two sets of rings offering the same strength, the steel rings will be 40% heavier, and also 60% smaller which means reduced scope contact surface area, which means less friction and that the rings need to be tightened more and more likely to lead to ring marks or crushing the ring.

Therefore, I am not sure why steel is used for scope rings.

Can the steel ring proponents shed some light into this?

There are more than just two mechanical advantages of steel over aluminium, and like anything there are differences in aluminiums and steels. Another reason steel is used for barrels is heat tolerance. The aluminium rings need to be made from an appropriate grade of aluminium. Areas that can let aluminium scope rings down are the high stress areas, the threading and the contact area with say rimfire scope dovetails.

Aluminium is generally softer than steel.
We are talking about clamping something soft (aluminium rings) to something hard (steel receiver).

There are many possible variables, but the gist of it is; under repeated recoil it is possible for the aluminium to mar or peen under the superior hardness of the steel to a point where they can become loose.
If you look at old alumimum rings that have been on a rifle with a reasonable amount of recoil, sometimes you will see that the recoil bearing surfaces of the rings are deformed where they have been repeatedly subjected to pressure by a much harder material.

IMO, alumiunium rings require a greater contact area with receiver in order to mitigate the potential for the softer material to deform.
Both have their place. Some of the best mounts in the world are made of aluminium (spuhr), but they also have huge contact areas between the steel and aluminium.
I would be perfectlu content with for example steel optilocks which dont have much of a contact patch. But I would not want aluminium optilocs as the contact area would be too small to have good longevity without deformation.

A couple of little points. There is a big difference in modulus of steel and aluminium, steel is much stiffer. You cant really say steel is this much stronger than aluminium, there are huge variances in strength of both. Friction is not dependent on contact surface area.

When it comes to mounts and rings you get what you pay for .
Doesn’t matter to me Steel or Alloy , I have both and payed $$$$$$ for both .

Originally Posted by Chilli_Dog

A couple of little points. There is a big difference in modulus of steel and aluminium, steel is much stiffer. You cant really say steel is this much stronger than aluminium, there are huge variances in strength of both. Friction is not dependent on contact surface area.

Hi there, I would disagree on two points.

firstly, steel is definitely not the stiffer of the two. It is well accepted that when it comes to bicycle materials, steel frame offers a more forgiving, shock absorbing ride. aluminium frames on the other hand is harsher, more punishing because it is stiffer.

secondly, I cannot agree that friction is not dependent on contact surface area. If so all race cars would have skinny tyres.

I've used Talleys aluminum rings on 3 different rifle set ups now, a 270win and 2 different 270 wsm setups and never had an issue with any warping or deformation.
Cant see myself changing rings anytime soon.....if it ain't broke.....

Originally Posted by ChrisW

Aluminium is generally softer than steel.
We are talking about clamping something soft (aluminium rings) to something hard (steel receiver).

There are many possible variables, but the gist of it is; under repeated recoil it is possible for the aluminium to mar or peen under the superior hardness of the steel to a point where they can become loose.
If you look at old alumimum rings that have been on a rifle with a reasonable amount of recoil, sometimes you will see that the recoil bearing surfaces of the rings are deformed where they have been repeatedly subjected to pressure by a much harder material.

IMO, alumiunium rings require a greater contact area with receiver in order to mitigate the potential for the softer material to deform.
Both have their place. Some of the best mounts in the world are made of aluminium (spuhr), but they also have huge contact areas between the steel and aluminium.
I would be perfectlu content with for example steel optilocks which dont have much of a contact patch. But I would not want aluminium optilocs as the contact area would be too small to have good longevity without deformation.

Most weaver and picatinny scope rails are made of aluminium. in fact I do not know any rail that is made of steel. Most people happily screw these rails onto the steel action. I have never heard of aluminium scope rail breaking either.

With weaver or picatinny scope rail, you also do not have have slipping issue.

Why would you reduce the clamping area of the steel ring rather than keep it at optimum and just thin out its section? that makes no sense.

I have never had an optilock or leupold steel mount move or come loose or give me any issue other than being slightly heavy and some surface rusting.
I have had a number of (cheap) alloy mounts move after the rifle has been knocked or dropped.....top quality ones may be better and one would hope so.

Originally Posted by Ultimitsu

Hi there, I would disagree on two points.

firstly, steel is definitely not the stiffer of the two. It is well accepted that when it comes to bicycle materials, steel frame offers a more forgiving, shock absorbing ride. aluminium frames on the other hand is harsher, more punishing because it is stiffer.

secondly, I cannot agree that friction is not dependent on contact surface area. If so all race cars would have skinny tyres.

You dont have to agree, however steel has an elastic modulus of around 210GPa 7075 t6 is around 70 GPa, no where near as stiff. Your bike frame analogy is confusing section properties with material properties, in theory you could make a steel bike frame that was stiffer and lighter than an alloy one however wall thicknesses would be way to thin to be practical. Tyre force transmisson is limited by the tyre material

You do not know of any rails made of steel?


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Originally Posted by Ultimitsu

Hi there, I would disagree on two points.

firstly, steel is definitely not the stiffer of the two. It is well accepted that when it comes to bicycle materials, steel frame offers a more forgiving, shock absorbing ride. aluminium frames on the other hand is harsher, more punishing because it is stiffer.

secondly, I cannot agree that friction is not dependent on contact surface area. If so all race cars would have skinny tyres.

Steel is definitely stiffer than Aluminium. Physics say so.

Unlike strength, which can vary from grade to grade or even coil to coil, Young’s Modulus is constant for a given metal and is independent of heat treatment, processing, or cold work. Young’s Modulus for steel (29 million PSI) is three times that of aluminum (10 million PSI). This means that for a fixed geometry, a part made out of steel will be three times as stiff as if it were made out of aluminum. In other words, an aluminum part under load will deflect three times as much as a similarly loaded steel part.

The thickness and shape of the formed part also contributes to its stiffness. Stiffness is proportional to the cube of the thickness. To neutralize aluminum being one-third the stiffness of steel, an aluminum part must be made 44 percent thicker than the steel part. Even with this increased thickness, there is a potential for weight savings since aluminum is one-third the density of steel.

There are a few steel picatinny rails out there. I have a Warne steel rail on my Rem700, with Leupold steel rings. It's not a hunting rifle so the weight is not a factor. Have alloy picatinny rail and vortex alloy precision rings on my hunting rifle, and they just work too.

Originally Posted by Ultimitsu

Most weaver and picatinny scope rails are made of aluminium. in fact I do not know any rail that is made of steel. Most people happily screw these rails onto the steel action. I have never heard of aluminium scope rail breaking either.

With weaver or picatinny scope rail, you also do not have have slipping issue.

https://www.egwguns.com/scope-mounts...a-ambidextrous

Originally Posted by Ultimitsu

Hi there, I would disagree on two points.

firstly, steel is definitely not the stiffer of the two. It is well accepted that when it comes to bicycle materials, steel frame offers a more forgiving, shock absorbing ride. aluminium frames on the other hand is harsher, more punishing because it is stiffer.

secondly, I cannot agree that friction is not dependent on contact surface area. If so all race cars would have skinny tyres.

You are correct on the points I have highlighted.

One theory is that when your picatinny rail is made of steel, it expends at the same rate as the receiver therefore having less chances of inducing stress during variation of temperatures.

Also, just to give an idea (but I am not sure what steel is used for scope mounts):

https://www.makeitfrom.com/compare/7...l-Carbon-Steel