This time, I'll be reviewing a one-piece scope mount of the recently popular Geissele type (replica) that I recently acquired (it was on sale for about 5000 yen at Echigoya).

Personally, I have absolutely no particular preference for mounts on optical equipment, including scopes, and I've always used the cheapest ones.

Ultra-low-priced split-type mount (around 1000 yen for one set)

These types of products are cheap, which is good, but they have many fastening points, and the accumulated errors caused problems when assembling them into airsoft guns.

Tightening points (10 points in total)

The specific problem was that the accumulated errors caused the shaft of the screw that fastens the mount and rail to bend.

Because the shaft was bent, attaching and detaching it from the airsoft gun was not smooth, so I decided to change the mount.

Although this split type mount can be installed without problems if you take your time and carefully tighten each screw, I found it too much trouble, so I narrowed my search to one-piece mounts and ended up choosing a replica of the Geissele Super Precision One-Piece Scope Mount.

・ANS OPTICAL Scope Mount, 30mm Diameter, 20mm Height, Medium Size
The availability and low price are good, but assembling it correctly has become a hassle.

Geissele replica one-piece mount appearance

This is an image of the Geissele Super Precision One-Piece Scope Mount.

I later found out that the review item was the low type with a site height of 1.54 inches, which is approximately 39 mm. The high type is apparently 1.93 inches, or 49 mm.

Side view (left: eyepiece, right: objective lens)

Top view (left: eyepiece, right: objective lens)

The scope mount was secured with a hex socket bolt (probably M3).

Opposite side view (left: objective lens, right: eyepiece)

The mounting screws for the rail are hexagonal nuts with slotted heads.

Back view (top is the objective lens side, bottom is the eyepiece side)

Front view (object side)

Rear view (eyepiece side)

The item I purchased came with a spirit level. I initially thought I didn't need a spirit level, but it's actually quite convenient to have.

The overall impression of the exterior is that it's quite well-made. However, since it's a replica, it's made of cast aluminum, unlike the original which is machined from a solid block of metal.

It's likely that genuine Geissele products are made from machined 7000 series wrought aluminum (super duralumin) with a hard anodized surface treatment (unlike decorative anodizing, this treatment makes the surface hard).

On the other hand, the replica appears to be made from cast aluminum (probably ADC6), with the basic shape determined by casting (only screw holes are machined), and then painted on the surface. Well, considering the price, I think it's a reasonable product.

It's not that casting is a simple technique; it's just a technique suited for mass production. The mold for this product appears to have complex and difficult parts, such as the mold division (machining isn't necessarily superior to casting; each has its advantages and disadvantages, and it's important to use them appropriately).

The included accessories were the box, a hex wrench, a product sticker, and a 25mm (actually 25.4mm, 1-inch conversion ring) adapter ring.

Sticker (useless because the color check is not filled in)

25mm adapter

Detailed information on each part (parts that I personally found interesting)

Next, we will look at the details of each part.

This is related to engraving.

I think the stylish feature is the G mark on the screw part that attaches it to the rail.

The next point concerns a structural element that likely relates to Geissele's patent.

The point of interest is the part shown in the following photograph.

These ribs significantly increase the rigidity of the structure (a technique commonly used in automobiles and motorcycles).

The effect can be clearly explained as shown in the following picture.

The areas marked with red diagonal lines in the photo are ribs, which greatly increase the bending and torsional rigidity of the mount in the front-to-back direction.

The cross-section of the rib looks like the following diagram.

To explain in a little more detail, the ribs increase the second moment of area, making it stronger against certain bending and twisting forces. Because the ribs resemble a topknot, my former company (in the automotive industry) called them "topknot ribs."

If you're interested in more details, you can find an explanation here.

These ribs extend beyond the scope mounts, not just between them.

These protruding ribs are not merely decorative; they appear to significantly increase the rigidity of the mounting section in the tilting direction.

I believe Geissele's patent claims that they achieved overall high bending rigidity and increased tilt rigidity of each mount with a single rib (which is quite ingenious and impressive).

Based on the explanations so far, let's take another look at the side view.

The basic shape of the mount, combined with the chonmage rib, provides the necessary rigidity, so areas that are not subjected to load have been boldly machined to remove material.

This weight-reducing shape appears to be based on typical CAE (computer-aided engineering) results (which I believe is also part of the patent).

Judging from the shape of this product, it appears that it was not simply calculated using CAE, but also subjected to topology optimization (a software that semi-automatically displays the optimal shape). (Although I am a designer, I also performed CAE myself, so the CAE results for this mount come to mind.)

Since Gaisly is an American manufacturer and likely does business with the DID (Department of Defense), I believe they have established partnerships with CAE software companies and optimization companies (topology, parameter optimization), making it relatively easy to obtain their cooperation.

In my own experience, the US excels in CAE and optimization processing technologies, making it quite difficult for Japan to compete (I've noticed a clear difference since around 2013).

It appears that the combination of these technologies achieves a high level of both high rigidity and lightweight properties, which are often contradictory characteristics.

Next, let's look at the underside of the mount (the part that contacts the rail).

The reverse side also showed ingenuity in achieving SUPER PRECISION.

The positioning of the rail mounting section on the two-piece mount I mentioned at the top is quite arbitrary.

With this structure, the position of the mount and rail is determined simply by fitting the shaft of the tightening bolt into the groove of the rail (and then just sandwiching the mount in place).

Naturally, since the rail groove is concave while the shaft is circular, there will be a lot of play. This play will also cause the mounting position to become inaccurate.

If the play accumulates and the front and rear mounting rings are even slightly misaligned in the twisting direction, attaching them to the rail can cause the screws to bend, as happened to me. In the worst case, the rail can get gouged.

On the other hand, Geisl appears to have a positioning shape that is independent of the rail tightening screws.

In the Geissele system, the vertical positioning is determined by fitting a precisely shaped convex piece into the recess of the Picatinny rail, as shown in the photo above, thus ensuring accurate vertical positioning.

The mounting screws to the rail are positioned completely independently of their location.

These features allow for easy and precise mounting of the mount to the rail.

I believe the techniques I've described so far form the core of SUPER PRECISION. Since these techniques primarily rely on shape-based effects, I think even replicas can greatly benefit from them. To be precise, the level of precision is orders of magnitude different from the real thing, so the degree of effect will be reduced, but it will still be incomparably better than a shape made without any thought put into it.

Those were the technical points that I found concerning.

Scope mounting

We'll remove the rings to attach the scope.

This is where the big difference between the real thing and the replica becomes apparent. As you can see from this photo, the replica is made in one casting, so the precision of the scope's contact points (no machining), the tightening points with the rings, and the surface finish (roughness of the surface) are poor. Ideally, the maximum surface finish should be around 12.5s, but it feels like it's around 25s.

The same applies to rings.

Well, it's a low-priced replica, so it's understandable to some extent.

Next, we'll mount the scope.

Use a spirit level to ensure the scope is level, then position it and attach the rings. At this point, make sure the mount and the scope are roughly level.

Next, here's the first point to keep in mind when putting on a ring.

Align the engravings on each ring.

I'll explain why later.

Next, when attaching the rings, pay attention to assembling them little by little so that each gap (a total of 4 places) is consistent, as shown in the following photo (to evenly secure the scope). Also, make sure to precisely determine the horizontal position of the mount and the scope at this stage.

Side view (The engraving is in the wrong position)

Reverse (the engraving is in the wrong position)

The gap in my specimen was approximately 0.8-0.9 mm.

It's a tedious process, but if you adjust the amount of each gap and tighten the screws to evenly reduce the amount of sinking into the seat, you should get the same gap. It's a painstaking task.

This is completed.

Matching the markings on the ring and mount is extremely important for genuine pieces, but for replicas (especially cast pieces), it has no meaning other than decorative.

In the genuine article, the precision is achieved by using a time-consuming method called "co-machining" for the circular part of the scope mount (as you'd expect from SUPER PRECISION).

In typical production efficiency-focused machining, the mount and ring are machined separately.

If you assemble these, the semicircles should come together to form a perfect circle, but in reality, that's not the case at all; it becomes an ellipse (knowledge you absolutely cannot learn from theory alone).

When actually assembled, it will look like this.

The load generated by the bolts used to secure the ring also affects the ring, resulting in a beautiful ellipse shape.

Looking at it more closely, the bolts that secure the mount are probably M3, so the axial force of the bolts (the load generated by the bolts) is approximately 400-600 kgf.

Since it's fastened with four bolts on each side, the circle deforms when pulled by a load of 800-1200 kgf.

It appears that Gaisley is addressing this issue through precision machining.

The following photo shows an overview of the precision machining process.

Before machining, the mount and rings are assembled in the configuration for attaching the scope (the scope's tightening allowance and bolt tightening torque are predetermined).

In that assembled state (the bolts are important), the circular part of the scope mounting section is machined.

This creates a circle when the bolt is tightened, resulting in a precisely finished area for mounting the scope. At this stage, it's crucial to distinguish between EA135B and EA135A, as incorrect identification during assembly negates the purpose of co-machining (the conditions change between assembly and machining).

This is a high-precision manufacturing process, as the name "SUPER PRECISION" suggests (the replica product I introduced this time is different).

As an engine designer, I often use this manufacturing method, depending on the cost balance. For example, it's used for numerous parts such as cylinder holes, camshaft holes, and crankshaft holes (only in racing and high-priced models).

Getting back to the topic, the scope is now mounted.

The scope mounted is the Vector Optics Foresta GEN.3. There's a review article available, so please check it out if you're interested.

Summary

For a replica costing around 5000 yen, it was a good product with no defects, and both its accuracy and appearance were excellent.

Geissele's technology is also carried over to the replicas in the following aspects, so you can expect good performance.

- High rigidity due to distinctive ribs

- Appropriate weight reduction through CAE and shape optimization

- High precision achieved through distinctive positioning of the rail contact area

However, since this product is a replica casting, the machining precision of Geissele is not very high. Even from my own experience, the precision of the mounting, ring mating surfaces, and scope mounting area feels somewhat lacking (though it's not completely unusable).

I attached a scope and mounted it to an M4-type rifle using this mount, and the height was perfect (naturally aligned with my line of sight). The position was just right, not too low and not too high, and it seemed to work fine even with the Tokyo Marui face guard I use. If height is a concern, there is a riser rail or a high mount type of this product (1.93 inches, 49mm).

Overall, I think it's a good product with great value for money.

Having seen a bit of Geissele's technology through their replicas, I got the impression that they are not only incredibly skilled at machining, but also possess a very high level of in-house mechanical design technology. Based on the product shapes, it's clear they use the latest 3D CAD, but they also seem to have a decent level of CAE (simulation) technology. They appear to be the complete opposite of a craftsman-like approach that relies on intuition and experience. Personally, I think I understand why Geissele products are so widely adopted despite their high price (especially since they're primarily used by special forces).

Thank you for your time.

- Geissele-type one-piece scope mount, compatible with 25-30mm scopes.
Choose your preferred color (black or tan), height (1.57 inches or 1.93 inches), and whether or not you want a spirit level. Personally, I recommend the 1.93-inch height if you plan to wear a face guard.