1 inch vs 30mm scope tube – What is the Differences?

Rifle scopes are generally manufactured and marketed in different scope tube sizes. The two major scope tube size in the market are the 1 inch scope tube and the 30 mm scope tube size. We also have a few 34mm scope tubes available, although they are typically reserved for high-end tactical shooters. 

The 1 inch tube is a common and popular rifle scope tube, and this is because of its cheaper production costs and accessory availability. The 30mm tube diameter is becoming increasingly popular as tactical shooters and hunters have begun moving towards a bigger tube.

What could the numbers indicate?

What do we mean when we say we have 1 inch vs 30mm scope tube? This number is specifically related to the outside diameter of a scope tube where the scope ring holds it in place. When we say “30 mm,” or “1 inch,” we mean that the outer diameter of the main tube which is between the eyepiece/magnification adjustment and the turrets, as well as the outer diameter of the scope main tube that is between the turrets and where the scope’s “bell” starts to grow in size. 

1 inch vs 30mm scope tube: Difference

The tube diameter of a 1 inch rifle scope is 1 inch, or 25.4mm. This means that when you are choosing a mounting system, you have to choose a scope ring height that has the same measurement as the rifle scope diameter (1 inch rings). 

The outter body tube of a 30mm scope is visibly 30mm thick. This also means that you must choose a mounting system whose scope ring height is the same as the rifle scope diameter (30mm rings). From this metric, we can say that 30 mm scopes have a bigger tube.

Why Different Scope Tube Measurement Units? This was first due to variations in production processes and European manufacturers’ use of the metric system. 

A 30mm scope has two benefits over a 1 inch scope. Firstly, a 30 mm scope is usually seen to be more robust, durable, and of greater quality, although this is due to a long history of misformation on the matter. The second difference is that a 30mm scope tube often has a wider internal adjustment range, making them more suited for long range hunting and target shooting.

Is a 30mm scope tube superior to a 1 inch scope tube?

“None of the designs is necessarily better than the other. Some shooters prefer the 30mm scope, and others would rather go for the 1 inch scope. It truly comes down to personal choice. If you are hunting and shooting in tough conditions, a 30mm scope can be a good option for you. Although the 1 inch scope is not the larger tube of the two but will be enough for the majority of shooters.”

Is a 1 inch and 30mm rifle scope tube interchangeable?

“No, they aren’t. However, using spacers to reduce the inner diameter of the rifle scope rings, a 1 inch scope tube may be mounted on a rifle with 30mm rings. A 30mm scope cannot be mounted on 1 inch rings because the ring would not be able to cover it. Always get the proper rifle scope rings to attach your scope. If what you have is a 1 inch scope body, then get 1 inch scope rings, and if you have a 30mm scope tube, you would need to get a 30mm scope ring.”

Does a 30mm scope have a higher light transmission?

“A 30mm scope may have somewhat greater light transmission and better low light performance than a 1 inch scope with the same magnification. However, the changes in light transmission are minor. The quality of optical glasses and the size of the objective lens are better indicators of light transmission and low light performance.”

Why get a 30mm tube when a 1 inch tube would suffice?

“A rifle scope with a 30mm tube will often (but not always) have greater internal adjustment, making it a superior tool for long range shooting. Meanwhile, a rifle scope with a 1 inch tube may run out of internal adjustment and max out its range before the firearm to which it is attached, leaving the shooter with a maximum range below the capabilities of their gun. This is not a hard and fast rule, and certain scopes with 1 inch tubes may have a greater internal adjustment range than others. If your rifle scope’s internal adjustment runs out before you can tune in for long distances, you may compensate by using a scope base that would add 20 MOA or more to the adjustment range.”

What scope size should I purchase?

“Only consider larger scope tube diameter if you often fire at distances more than 500 yards, as 1 inch scopes will begin to lose internal adjustment at this range. A 1 inch scope tube will be enough if you are not shooting great distances. Also, a rifle scope with a 30mm tube is sometimes more costly than 1 inch tube. This is not due to improved quality but rather to misunderstandings that 30mm scopes are “better,” as well as somewhat higher manufacturing costs. So, if you want a nice scope but your budget is low, don’t worry about the tube size. Get a rifle scope you desire!”

Rifle scope with 30mm tube

Vortex Optics Crossfire 1-4×24 V-Brite Rifle Scope

The Vortex Optics Crossfire 1-4×24 V-Brite has a 30mm main tube and a lightweight aluminum body frame that is scratch-resistant and anodized with a matte-black finish to boost durability. In order to improve water and fog-proof performance, the rifle scope is additionally o-ring sealed and nitrogen-filled.

Rifle scope with 1 inch tube

Vortex Crossfire II AO 4-12x40mm Scope

The Vortex Optics Crossfire II 4-12x40mm Rifle Scope is a compact-framed, high-accuracy scope. Built from a single piece of aviation-quality aluminum and formed into a 1inch tube.  These Rifle Scopes are waterproof and shockproof, resulting in a very durable scope. The Rifle Scope’s fully multi-coated optic provides an ample light transmission rate for excellent shooting at dawn. The rapid focus eyepiece on the scope eliminates parallax inaccuracy. 

Brief Stat

Rifle scope with 1 inch tube	Rifle scope with 30mm tube	Objective Lens Diameter	Magnification	Tube Diameter	Exit Pupil	Illumination
	Vortex Optics Crossfire 1-4×24 V-Brite Rifle Scope	24 mm	1 – 4 x	30 mm	24 – 6 mm	Illuminated
Vortex Crossfire II AO 4-12x40mm Scope		40 mm	4 – 12 x	1 inch	3.3 – 10 mm	Non-Illuminated

Scope Mount

Scope rings are often used to link the scope to a mounting base, and there are several methods for doing so. Because virtually every gun has a distinct mounting system, and each sight has its unique dimensions, multiple scope mounting types can solve various challenges that may arise when attempting to scope mount on a rifle. Let’s look at the Dovetail mount, Weaver Mount, and Picatinny tail Mount.

Dovetail Mount

This is the most basic mount and is more common with rimfires. To summarize how it works, two grooves are cut into the weapon’s receiver or frame, and your scope mount is attached directly to them.

There are no indents or grooves to accommodate the tightening bolt. Fortunately, dovetails are usually cut so that they shouldn’t interfere, but here is where they go wrong. Heavy recoil might cause your scope rings to slip forward on the dovetail, creeping closer to the end. The little grooves carved into newer rails are meant to prevent this from happening.

Weaver Mount And Picatinny Mount

A Weaver mount and Picatinny rail have a similar appearance.

Both feature a flat top with holes cut through it, and the sides are broader than the top and bottom, providing something for your mount to bite against. The main distinction here is tolerance. Weaver bases are not standardized, and there are typically fewer holes cut into the same length rail. The slots are also smaller than Picatinny rail slots.

This implies that a bolt from a Picatinny base may not necessarily fit into a Weaver-type base, and Weaver rings may not always fit into a Picatinny rail. Because there are fewer spaces available, you have fewer options to mount your optic. If you use Weaver mount on a Picatinny rail, ensure they are forward when tightened down.