Why the Wilcox J-arm is bad. And why Wilcox should feel bad.

The Wilcox J-arm remains very popular despite some very fundamentally flawed design and execution flaws.

The steel pin + drum detent system that Wilcox likes to employ so much uses an aluminum drum and a steel pin. A hard impact will cause the steel pin to begin to damage the aluminum drum, developing a fairly noticeable wobble.

Witness video here:

This particular J-arm was used extensively and wobbles significantly when employed for use with the left-eye. Since there is no tightening mechanism on the detent, in dynamic on-the-move situations, you end up with a PVS14 that bounces up and down as you move – this has the very real effect of being extremely disorienting, if not nauseating. This unit was actually sent back to Wilcox for T&E and returned back to me, with a note saying that the “unit functions as designed”. I’m fairly confused by their assessment. My only way to rationalize their response is that this amount of play was judged to be negligible and/or they have so many of these units exhibiting this exact symptom that it has now become common-place. I also suspect that if/when these arms become worn out, that operators in the field can simply request another from the unit armorer and the problematic mount discarded.

Another flaw in the Wilcox J-arm lies in the knurled-knobbed angle adjustment mechanism. If used in conjunction with a FTO (force-to-overcome) mechanism (eg: INVG or Rhino 1 or 2), under hard-use, the bolt has a tendency to snap. This has occurred at least twice to members in our team. In an effort to reduce headborne weight, Wilcox has chosen to use a smaller-gauge bolt.

One last overall complaint that I have with Wilcox is that, compared to Norotos products, all of their dovetails and interfaces just seem to have at least SOME play in them. An argument can be made that this was intentionally done with the knowledge that the equipment will be used in harsh, potentially sandy environments and if the tolerances were made too tight, that debris would cause the interfaces to jam.

There ARE some merits to the Wilcox dovetail J-arm though – namely:

  1. The ability to swap between left to right eye very quickly (from casual conversations with a large number of PVS14 users, I have found that all users have a “preferred” eye, and therefore, while the idea and ability is novel, have never actually used this feature)
  2. Large knurled knob for tightening the arm against the PVS14 (again, once installed and torque’d, I have yet to see this being all that useful)

In conclusion, I can’t – in my good conscience – recommend the Wilcox dovetail J-arm. The exorbitantly high cost coupled with a myriad of issues which can develop over the course of ownership represents a low-value proposition.

On the other hand, I can recommend the Norotos Dual Dovetail Adapter.

The DDA is made out of a very simple machined delrin with 2 dovetail pieces, the simplicity of the design lends itself to a very practical outcome – there are no points where the unit can fail. The user simply attaches the DDA to the PVS14 via the large Philips screw and both units are now treated as one. From that point on, the user often already has a preference of a left or right and and would attach it to their helmet NVG mount as such. In rare situations where it would need to be flipped, the user can dismount the NVG and re-insert it into the mount.

Due to its extremely robust nature, you can freely use mounts like the INVG’s FTO without fear of snapping bolts or worn-out detents.

The legacy DDA did not have a horizontal adjustment, which became a complaint for some users. The now-updated design featuring “True Horizontal Adjustment” (THA) now ships with both a FIXED dovetail and an adjustable horizontal travel dovetail. This allows users to offset the dovetail adapter to their desired face shape without having to shift the helmet around. However, users who do not have an issue using the single-piece dovetail can continue to do so, and dismount the adjustable dovetail for a reduction in weight.

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