The first question we should be asking is “why not use the PVS-14 behind the scope as you would with a red-dot?”
Two problems arise with setting the PVS-14 in back of the ACOG TAS01NSN:
The ACOG must be so far forward to leave rail space that the short eye relief of the 4x ACOG will not be user friendly in daylight.
The tritium is too bright for the PVS-14 as it’s designed for low-light shooting without NODs.
Besides, if you put the PVS-14 in front or behind, you still have parallax error.
The red-dot design allows for offset (parallax induced) viewing and corrects the error to the limits of the dot’s physical design with a curved piece of glass that the reflection of the LED bounces off of.
This is why they are the preferred way of passive shooting with NODs.
With a PVS-14 in front of the ACOG you are now putting a “screen” in front of your scope that if adjusted to infinity will work to present an “inline” image allowing POA/POI to be the same if they happen to line up… In theory.
In practice, unless you have a way to adjust the PVS-14 to be in line with the scope, it is going to have parallax error. This was possible with a device called a “Zero Lens” from Black Optics but unfortunately it seems to no longer be available, and it came with a crazy $1695.00 MSRP so that’s a non-starter for me.
One issue that arises is the ability to have enough gain on the PVS-14 to present an image the ACOG can pick up to be able to impose the reticle over the target. This means you will need a higher end unit to get the most out of this technique.
WHAT THE INTERNET SAYS
…the image is 100% horrible. I’ve done… 4 night shoots with one in front of the RCO and POI shift is minimal at 25 meters, shooting under CQB conditions, but anything requiring ANY precision would be out of the question unless it was a permanent, dedicated NV set-up.
Focus is not the issue but usually a POI/POA shift due to the mis-optical alignment of the two optics. Yes, some have used a 14 out in front of an ACOG, but this is hit or miss at best.
PVS-14 In Front of ACOG? - AR15.COM
It will work but it will not be accurate. The reason is the two scopes are not optically aligned. Light has to enter the scopes on the same plane/angle or you will get a POA/POI shift. You will never get reliable accuracy by doing this. The PVS-14 is not designed to do this.
NOTHING VENTURED, NOTHING GAINED
In the end, you won’t know until you try it. So, I did.
It doesn’t work and unless you have a device like the BLACKOPTEX, you are wasting your time even buying the mount IMO.