There are so many optic mounting options out there, so the question is when to use a riser mount adapter? When should you use a tall height optic mount?
Both of them work! Sometimes one over another is preferred, sometimes no riser is necessary, but the key is to tweak the optic height until optimal cheekweld position & eye to optic alignment.
Here are couple key questions to help the shooter decide:
- Where does the receiver top rail sit relative to the rifle stock?
- How much cheek does the shooter want on the stock?
- How much flexible eye box and head movement wanted?
- Shooters' neck and cheek dimension differences
This is very much a "pick your adventure" type of configuration, and here are some tips and examples:
When To Use A Riser Mount Adapter Rail
The best times to use a riser mount adapter rail:
- Raise red dot optic height if cheekweld position sits low
- Raise red dot magnifier to align with the primary optic
- Raise red dot magnifier if magnifier riser plate are not available
- Reduce neck strain for shooting in prone positions
- Clear optic from 12 o'clock position mounted handguard accessories
- Convert a low mount height optic to lower 1/3rd (Usually adding 0.8" - 1" height)
- Consolidate a red dot and magnifier combo on one quick detach rail
- Use on polymer top rail to mount optic with aluminum mounts
- Bridge handguard and receiver rail
- Raise angled offset red dot mount to align with the bore
- Use for non optic related applications when see fit
When To Use A (Single Unit) Tall Optic Mount
The best times to use a tall optic mount:
- Use one tall mount to get the height you need without stacking height using a riser mount
- Get more up right shooting position
- Reduce neck strain for prone position just like the riser mount
- Clear a gas mask
- Clear the fixed front sight post for better situational awareness
- Buy specific mount height that you know works
- Tall mount already integrated with the optic (Such as the EOTECH EXPS3 with and Israeli made optics)
- Keep it simple
Common Optic Heights
- Absolute Cowitness - 1.43"
- Lower 1/3rd - 1.57"
- Night vision height - 1.93"
Check out the Scalarworks NV LEAP mount
Potential Problems With A Riser Mount
A riser mount can introduce some slight alignment errors along the top rail if:
- Not torqued correctly can lead to misalignment
- Out-of-spec riser mount on the top rail leads to misalignment
- Riser mount without recoil lug can cause poor alignment if the rail length is long
The error can magnify when mounting other precision equipment (Optic) on top.
Please only use precision-machined products from reputable companies.
Optic Configuration Examples
AK Type Rifles
AK rifles have inherently lower stock cheek weld positions relative to places where optics can be mounted.
Generally speaking, a low optic mount works well on the AK without any riser.
AR Type Rifles
The AR15 type rifles work very well with lower 1/3rd or night vision height optic mounts.
So the shooter doesn't have to press their cheeks hard into the stock to acquire the sight, and also allows a much more flexible eye box and head movement.
Receiver With Slightly Raised Top Receiver Height
Sig MCX, HK 416, FN SCAR, M4A1 with ARMS S.I.R handguard.
These rifles have a slightly raised top rail height than a standard A2 AR upper receiver.
- A standard 1/3rd co-witness height mounts on these firearms will be as tall as a night vision height mount
- An absolute co-witness height automatically becomes a 1/3rd co-witness height mount
- Try an adjustable cheek height rifle stock to get the optimal cheek weld position and good eye to optic distance
An extra tall mount such as Unity Tactical FAST mount or FTC mount is not necessary because they will sit too tall on these rifles, which can lead to high optic height over bore issues.
The standard IWI X95 rifle works much better based on community feedback to have a riser top rail so the shooter can get behind the optic better without pressing the cheek hard into the rifle, and also allow for better head movement behind the optic when operating in tight spaces.
Here are a couple of options:
- Use a inherently tall optic such as EOTECH EXPS3 or Metrolight M21
- Try Manticore Arms' X95 overwatch full length top rail to raise 0.5"
Most shotguns preferre using low optic mounts. It's very rare to see people use a tall mount on a shotgun.