Spuhr SP-6602 Scope Mount 36 mm / 38 mm / 6 MIL (20.6 MOA)

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With a rare 36 mm main tube, the choice is not done with "approximately fitting." Reducer sleeves, 35 mm rings, or 40 mm bodies are not a clean alternative. At the same time, with an inclined mount, not only the rear height determines whether the objective, rail, and a possible front device have enough space.

The SP-6602 connects the 36 mm tube directly with a MIL-STD-1913 or STANAG-4694 rail. Spuhr designs it with 38 mm axis height at the rear ring plane and 6 MIL / 20.6 MOA inclination. The datasheet explicitly mentions 56 mm objective classes, extended Picatinny rails, and night vision equipment as the intended system environment.

The four strict selection criteria: The main tube must measure exactly 36 mm. The existing rail inclination is added to the 6 MIL. The elevation turret must reach the desired close zero point in the opposite direction. Objective and front device need sufficient geometric and optical reserve at their actual position.

6 MIL position the existing adjustment range
The mount does not create any additional mechanical elevation adjustment range in the scope. It tilts its axis relative to the rail and thus shifts which part of the existing range is available for longer distances. On a neutral rail, the total inclination is 6 MIL. Together with a 3 MIL rail, it becomes 9 MIL; on a base already inclined by 6 MIL, it is 12 MIL.
This sum must be compensated by the scope when zeroing in the opposite direction. A large total angle can be useful at distance and at the same time limit the achievable close zero point. Zero-stop, total optical adjustment range, and actually usable opposite range therefore belong in the same calculation before mounting.

Trainer tip: Plan backwards from the close zero point Do not start with the maximum possible inclination, but with the shortest zero point the rifle should safely reach. Subtract rail angle and 6 MIL mounting angle from the available opposite range. If the turret is close to the stop or the zero-stop cannot be set sensibly, the neutral SP-6002 is the technically better choice.

38 mm apply at the rear, not at the objective
Spuhr measures the 38 mm in inclined mounts at the rear plane of the rear ring. Due to 6 MIL, the scope axis drops forward approximately 0.6 mm per 100 mm longitudinal distance. For front clearance, the distance to the widest point of the objective housing or protective cap must therefore be considered.
If this point is 140 mm in front of the rear ring plane, the axis runs there mathematically at 37.16 mm. With a 70 mm outer diameter, theoretically 2.16 mm remain above a parallel, continuous rail; with 72 mm outer diameter, only 1.16 mm.
At 190 mm distance, the axis height mathematically drops to 36.86 mm. A 70 mm housing then leaves 1.86 mm, a 72 mm housing only 0.86 mm theoretical clearance. From these values, protective cap, manufacturing tolerances, dirt, and a sensible safety reserve must still be deducted. If the rail ends before the objective, the actual counter contour must be measured instead.
The designation "56 mm objective" refers to the diameter of the front lens, not the outer diameter of the housing. For the height calculation, only
h the real outer dimension at the narrowest point of the construction.

User tip: Determine objective clearance with two real measurements First, measure the outer diameter including the actually used cap. Then measure the longitudinal distance from the rear ring plane to this widest point. Subtract 0.6 mm from 38 mm for every 100 mm of distance, and then subtract half the outer diameter. The result is the theoretical clearance before safety margin.

The 36 mm rings have their own clamping sequence
The exact datasheet specifies 32 mm wide ring surfaces and 64 mm free space between the ring areas. Both clamping zones of the scope must be exactly and fully cylindrical there. A cone, a turret block, or a thickening does not belong under the ring.
For 36 mm tubes, the current ISMS manual prescribes a special sequence: First, the screws along the lower edge of the ring cover, referred to by Spuhr as the right mounting side, are tightened until no visible gap remains there. Only then are all ring screws fully tightened in a cross pattern. This distinguishes this tube size from a general "equal gap on both sides" mounting.
For the factory waxed M4 ring screws, 2.0 Nm or the lower value specified by the scope manufacturer applies. Additional lubrication changes the preload and must not be combined thoughtlessly with the specified torque.

User tip: Do not symmetrize the ring cover by appearance For the SP-6602, an optically equal gap on both sides is not the mounting goal. First close the lower or right cover edge designated by Spuhr, keep the tube aligned without tension, and then tighten in a cross pattern with the approved torque.

Front device and interfaces follow different axes
According to the datasheet, the SP-6602 is intended for use with night vision equipment. This means space and system preparation, but no automatic coaxiality with every front device. A device mounted on the extended weapon rail initially follows the rail axis, while the scope is tilted by 6 MIL due to the mounting.
The Spuhr interfaces also have two reference planes. Accessories on the ring covers follow the scope axis according to the manual. Interfaces on the mount body remain aligned to the mounting surface and thus to the rail. Laser, secondary optics, angle measurer, or other accessories must be positioned on the reference plane that their function actually requires.
The back of the supplied 10-degree wedge serves as a screw length gauge. This allows you to exclude before attaching interface accessories that a screw is too long and protrudes toward the main tube.

Fixed block mounting without offset
The 128 mm long body has neither QD lever nor cantilever. This is suitable if the optic remains permanently on the same weapon and eye relief as well as ring position are achieved within a continuous rail. On AR-style systems with optics position needed far forward, a cantilever mount may be required.
The 38 mm line fits well with straight chassis, large front contours, and setups with adjustable cheek rest. On a classic low stock, it can loosen cheek contact. The head should find the full field of view without having to lift the chin or change shoulder position.

Construction and mounting on the rail
The hard-anodized body is made of 7075-T651 aluminum according to the datasheet. Seven interface sets, the integrated bubble level, and diagonally split rings connect the optic mount with a modular accessory base. The Torx-20 screws are zinc-nickel coated and factory waxed.
When mounting on the rail, the body is pressed forward against the contact surface. The M5 clamping screws are first finger-tightened from the center outward and then tightened in the same order to 5 Nm. The supplied 10-degree wedge can ei
align a suitable flat underside of the scope to the integrated bubble level; without an accessible flat surface, another reliable leveling method is needed.

Our assessment
The strongest buying reason is not just the high profile, but the clean connection of a rare 36-mm tube with a front-tech-ready, inclined ISMS platform. If you specifically need this combination, you get a clearly defined solution without reducing sleeves.
The biggest risk of a bad purchase is an isolated view of the 6 MIL. On an already inclined rail, the sum can unnecessarily complicate the close zero point. Also, "designed for night vision" is not a blanket approval for axis height, mount, or optical tolerance of a specific front device.

Black-Raptor short summary: Buy if: a genuine 36-mm scope, a continuous rail, 38 mm rear head position, and overall sensible 6 MIL inclination come together and the calculated front clearance is sufficient.
Don’t buy if: the main tube is only similarly sized, the rail is already sufficiently inclined, the close zero point fails on the return path, the stock remains too low, or QD or cantilever is needed.

Scope of delivery

1 x Spuhr SP-6602 scope mount
1 x 10-degree leveling wedge with screw length gauge
1 x manufacturer’s manual

Scope, firearm, rail, night vision or front device, interface accessories, and torque tool are not included.

Suitable alternatives

SP-6002: same 36-mm rings and height, but neutral 0-MIL axis
SP-5602: same height and inclination exclusively for 35-mm tubes
SP-7602: same height and inclination exclusively for 40-mm tubes
SP-4602C Gen3: 34-mm alternative with 38 mm and 6 MIL

Technical data

Model: SP-6602
Main tube: 36 mm
Axis height: 38 mm / 1.5 inch at the rear ring plane
Inclination: 6 MIL / 20.6 MOA
Mount: MIL-STD-1913 / STANAG 4694
QD / Cantilever: no / no
Overall length: 128 mm / 5.04 inch
Ring width / free ring space: 32 mm / 64 mm
Weight: 273 g / 9.6 oz
Material: 7075-T651 aluminum, hard anodized
Interfaces: seven sets, integrated bubble level
EAN: 7340150701239
Torque: 5 Nm on the rail; 2.0 Nm or lower optics manufacturer value on the rings

Manufacturer exclusion: The SP-6602 does not fit the SAKO S20 and not rifles with two-piece rails according to Spuhr. 34-, 35-, and 40-mm main tubes are not compatible with the 36-mm rings despite similar model variants.

FAQ
Does 6 MIL extend the mechanical elevation adjustment range? No. The mount shifts the usable position within the existing adjustment range. The available return travel decides if the desired close zero point remains reachable.
What total inclination results with an inclined rail? The angles add up: on a neutral rail it remains 6 MIL, with a 3-MIL rail it becomes 9 MIL, and with a 6-MIL rail a total of 12 MIL.
Can a 35-mm scope be mounted in the 36-mm rings? No. The SP-6602 is designed for exactly 36 mm. Reducing sleeves or closing the rings beyond the intended measure are not approved solutions.
Why should one ring side be closed first at 36 mm? The current ISMS manual prescribes for 36-mm tubes to first place the lower or right cover edge without visible gap and then tighten all screws crosswise.
Is every night vision front device automatically aligned? No. The SP-6602 is intended for this system environment, but rail, front mount, device axis, and permissible optical deviation must fit the specific device.
When is the SP-6002 without inclination better? When the rail already has the required angle, the close zero point demands more return adjustment reserve, or no additional long-range inclination is needed.