Vortex Precision QR Extended Cantilever Mount 30 mm

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Vortex CM-404 · 30 mm · Quick Release
More forward offset for clean eye relief on flattop Picatinny setups. The Vortex Precision QR Extended Cantilever Mount CM-404 is a one-piece 30 mm scope mount with quick-release clamping. The extended cantilever design moves the optic further forward, creating the space many AR/flattop setups need for clean eye relief.
Crucial: The main tube must be exactly 30 mm. 25.4 mm and 34 mm are not interchangeable.

Our honest assessment

The CM-404 makes sense if a 30 mm scope needs to be mounted further forward on a Picatinny flattop platform and a quick-release mount is desired. Vortex specifies 37 mm center axis height above the rail top – a relevant value for head position and stock line.
It is not a universal solution for every firearm platform. On classic bolt-action rifles, the cantilever offset may be unnecessary; for 34 mm or 1-inch optics, the mount is mechanically incorrect.



Fits well if … you mount a 30 mm LPVO or scope on a suitable Picatinny flattop platform and need additional forward offset for eye relief.


Fits less well if … your optic has a 25.4 or 34 mm main tube, you need a particularly low classic ring mount, or no forward offset is required.


What the features practically change


Extended Cantilever The optic moves forward without the rings having to sit outside the intended rail base. This makes adjusting eye relief easier on AR-style flattop systems.
37 mm center axis height The center of the scope is, according to Vortex, 1.45 inches or about 37 mm above the Picatinny rail. This value affects cheek weld and head position.


Quick Release The mount can be removed and reattached faster than a classic screw clamp. For reproducible results, always use the same rail slot and check the fit afterward.


One-piece design Ring spacing and base form a unit. This simplifies alignment but limits positioning compared to two completely separate rings.


Limits, disadvantages, and avoiding bad purchases

The most important match is the tube diameter: CM-404 is 30 mm. Next are rail standard, available rail length, objective clearance, and the actual eye relief in your shooting position.
Quick Release does not mean you can assume identical point of impact after each removal without checking. Same slot, clean clamping surfaces, and a control shot remain the safe procedure.

Technical data with practical interpretation


Model Vortex Precision QR Extended Cantilever Mount CM-404.


Main tube 30 mm. Must fit the optic exactly.


Center axis height 1.45 inches / approx. 37 mm above Picatinny. Crucial for head and stock position.


Weight 8.9 oz / about 252 g. Stability and QR function add more mass than very light ring solutions.


Base Picatinny / Flattop. Forward offset is especially intended for AR-like platforms.


Design One-piece extended cantilever mount with Quick Release.


Mounting and secure checking
Make sure the firearm or platform is unloaded and checked before mounting. First determine eye relief in the real shooting position, align the optic without tension, and only use the torque specified for the optic and mount. After mounting, dismounting, or impact, check for firm fit and point of impact.
Scope of delivery
1 × Vortex Precision QR Extended Cantilever Mount CM-404.
FAQ
For which tube diameter is the CM-404? For 30 mm scopes. Other main tube diameters do not fit. How high is the optic mounted? Vortex states 1.45 inches or about 37 mm center axis height above the Picatinny rail. Why is the mount offset forward? The cantilever creates extra space on flattop platforms so the scope’s eye relief can be set correctly. Is Quick Release automatically repeatable? It makes removal and reattachment easier. For reproducible results, the same rail slot, clean clamping surfaces, and a subsequent check should be maintained. Is the mount only for LPVOs? No. The key factors are 30 mm main tube, matching Picatinny base, sufficient space, and a setup that actually needs the cantilever offset.

Black Raptor · Eye relief in front of optic
The right mount solves a geometry problem – it does not replace a compatibility check. CM-404 is a clear 30 mm Quick Release cantilever solution for suitable flattop setups. Tube diameter, height, and forward offset should be checked as a complete system before purchase.