I bought a shroud + TATM on ebay. Shroud came without screws. $8 + shipping from TNVC for 3 screws is a bit absurd IMHO. What is the thread-size? It seems to be an odd size. Why would they make it such an odd size unless their desire was to force people into buying proprietary screws at exorbitant prices?


UPDATE: I think I discovered the screw size (or at least narrowed it down to 2 sizes). It's a standard screw size but it's a not-so-commmon size. I think it's a 4-48 (UNF) but it could also be a British Association thread, 6BA (which is very close to 4-48 except the thread root angles). 6BA is a .1102" Major dia. (.085 minor dia.) X 47.85 tpi X 47.5 degree thread angle... It's an odd one. 4-48 is .112" Major Dia. (.086" minor dia.) X 48 tpi X 60 degree angle. Either way, I'm certain either screw will work. And both screws are "available", but neither is common. 6BA has to be ordered online, 4-48 may be available local but may take a decent search as UNF threads in the smaller sizes are very uncommon. I ran a 4-48 tap through and it works fine, but haven't found any 4-48 screws yet.

I tried 3 hardware stores locally and could not find the proper screws either. Your best bet is going to be buy a set of the screws from Norotos or TNVC.

Not blaming you. It's just impractical for me to pay shipping across the country on 3 screws that should be $.19 at the local hardware store.


That's aggravating. Why would they make it a proprietary thread spec? There is absolutely no reason for that unless they wanted to ensure absolute control on material/physical specs (possibly related to balistics of the helmet?) or they just want to force you to go through their channels to pay inflated prices.

Either way, I'm not getting them from TNVC because I actually want shorter screws. I'm using these on my home-made version of the Nightcap and the standard screws stick out way too far. I'm not paying $8 + $10 shipping just have to cut the screws down anyways. I'll just tap the holes to a common size if this is the case.

Does anybody know the actual thread-spec? Is it a UNEF maybe? I know its very, very fine thread.

Was the ebay shroud + TATM more than $8+shipping less than buying them retail?  Maybe the lack of screws is why.

If the screws are a special thread, it seems that you should be bitching at Norotos for the design, and thanking TNVC for offering them as available.

ETA:  Do you not have a caliper/mic and a thread pitch gauge?

afaik, all screws that are made to attach nvg shrouds to helmets are ballistic screws just like the chinstrap ones

they break in a certain way on impact so they aren't driven into your braincase

So as not to be perceived as a pure antagonist without offering any real assistance, I phoned up Norotos tech support.

They basically said that if the thread size and pitch was not listed on the data sheet, then the information is proprietary.  Coincidentally, they recommended TNVC as a source for the parts.

Here is my speculative read on this:
-Norotos claims proprietary data
-Folks don't seem to be able to find the proper screws at typical common sources
-The description of the Norotos product on TNVC says "custom made in-house-manufactured screws"
-Norotos has a big warning on their website about "knock-offs"

It may actually be good news that you can't find the screws as an indication you have purchased the genuine product versus a knock-off.

Sure was cheaper, but I have zero use for specialty screws because this isn't a ballistic application and i'm not paying the extra. Are you implying that I should pay that much money just because I got a deal on the mount? Like I said above, I'll just tap it if I have to. FWIW, The only people I've bitched about in this thread was Norotos making it proprietary. If you look above I commented that I understand that TNVC has very little to do with the cost. If you took that as bitching then you need to grow some thicker skin.

I have plenty of caliper/mics and thread pitch gauges but none that will fit inside a threaded hole that has a minor diameter of ~.080". Do you have some that will fit? If so, you must be a precision swiss watch maker. Next question, can you actually read the thread-pitch gauge that fits inside a hole that small? No? Well, that's why I'm asking here. It would be much easier for somebody with the proper screw to measure the screw than it would be for me to measure the inside of a tiny hole.


Maybe for some... considering that it's for ballistic reasons I get it. My point is to mount it on a night-cap, which has ZERO ballistic protection, I'm not buying special ballistic screws. I'll just tap it to a different size and use common screws. Thanks for your time everybody.

I have a beat up, but functional single hole shroud, with screw for the TATM that is free to a good home.

you'd really tap it and destroy its value to save 10bux? seems a little cray

Value is irrelevant if I don't plan to sell it; the value is what I place on it and to me the value is in providing a reasonably affordable mount inferface for my Nightcap. If I sink another $20 into the setup then I'm out more money but I've saved resale value; saving resale value only helps me if I sell it down the road.

FWIW, the resale value of TATM's and TATM shrouds is on a sharp decline right now so in another 5-10 years, if I need to upgrade for some reason I doubt it will have any realistic value left...

You should have sold them 1k screws in the wrong thread pitch.

I hope that you don't mind my snipping out the stuff not directly related to this response....

Certainly it would be much easier for some who has the proper screws to mic and thread gauge them, but that didn't seem to be getting much traction, so I suggested an alternative.

Of course the thread pitch gauge won't go in the hole, but if you purchase screws for 19 cents like you mention above, you should be able to determine the correct diameter even if the pitch is wrong.  You could then buy the same diameter screws with a thread pitch coarser and finer to see if either of those fits.  If none of the three fits, then you have two choices:

Buy the $8 proprietary screw set and pay the shipping, or re-tap the holes.  

If paying $10 shipping on an $8 item bothers you, then wait until you need something else and piggyback the parts.  If you never plan to buy anything else from TNVC, then you can wait until I buy something from them; I will piggyback the screws and ship them to you for free.

I just wish I could buy the ACH adapter arms for the universal shroud without buying the entire kit. I don't need the PASGT arms or ratchet strap and don't want to pay for the entire kit.

This is a classic cost-quality-schedule PM triangle.....pick any two at the expense of the third.

Buy the proprietary screws - quality+, schedule+, cost-
Drill & tap the existing fasteners - schedule+, cost+, quality-
Wait to piggyback the parts with another order - quality+, cost+, schedule-

There doesn't appear to be a three plus option.   The other four combinations [2x2x2=8] don't seem sensible to detail as they are three combinations of two minus's and only one plus, or three minuses.

If it's a completely proprietary screw (thread size/pitch included) then no off-the-shelf product would work. I tried all I have, 4-40 (too large and coarse), 2-56 (too-small but may be the right pitch, hard to tell), M4 too large, M3 too large, M2 too small... it's definitely an odd-ball. I was just hoping somebody knew thread-specs and could help me out. I appreciate you time and generous offer of piggybacking them then shipping free. But I think I'm going to hold off for now. This isn't a rushed project. I'm going to see if I can't dig up some more info or find some screws that I can measure...

It sounds as though you have bracketed all of the "standard" thread sizes/pitches within the range, so it must be something proprietary.  Norotos sure didn't want to talk about it when I called them.

As I mentioned in a previous post, that might actually be a good thing indicating you bought the genuine article.

I guess that it isn't a whole lot different than the substantially unusual 30.5mm x 0.75 pitch threads on the PVS-14 objectives.  I gave up on trying to find a 720 filter that fit properly.  At least the screws that you need are readily available, and c'mon $8 in the world of NV, really.

The shipping charges thing is all-too-common, and completely understandable.  When I need something from Brownells, I write it down on a list.  When the list gets long enough to justify the base shipping charge, or if I really need something quickly, or if something that has been out of stock for a while suddenly becomes available, I squeeze the trigger.  I do the same with other vendors.

A while back, I was questing the 0.035" allen wrench for PVS-14 focus lock ring adjustment.  The smallest I could find locally was 0.050", so I went online to the tried and true MSC.  They indeed had them for like 30 cents each, but with a minimum quantity of 25, and shipping of like $6 or 8.  I really wanted the 30 cent wrench, so I paid the $15....what is one's time worth?  Subsequently, about a dozen and a half other folks received free 0.035" allen wrenches.  I don't know how much USPS stamps cost because my wife buys the "forever" kind, but I am probably over $20 for a 30 cent tool.  BTW, I still have one or two spare allen wrenches left available for good homes.

I know, cheapskate... I'm very frugal... that's how I can afford night vision... it's also why I'm buying a used mount off ebay vs a new one from TNVC...  it's just who I am. I'm going to put the screws on my list and in the meantime see if I can't find out more about the thread-pitch. A 3-56 screw MIGHT fit, but it's a very uncommon screw size and I'm going to have to find one to try. We have a hardware store in the town 30 minutes north of me that has EVERYTHING. I just have to wait until I'm in town during business hours to see if they have any 3-56 screws to try in it.

Update in OP. I've narrowed it down to 2 different screw sizes. Trying to source some 4-48 UNF screws locally now...

you should buy a crap load of them and sell them for $5 each

nice job, glad you stuck it out and didn't tap new threads

It can be quite gratifying when a quest is successful.

oh I want that if you still have it!

Yes, accepting, and then conquering a challenge is very rewarding... I am motivated by challenges.

Did you get that shroud I sent?

Not yet... I've been watching for it though.

I just sent it USPS in a little yellow padded envelope so I don't know if it has tracking or not. I'll check and see though.