The Great M49 ARD Adventure
(or "Another Verbose Article by That Dave Guy")

3 March 1999
By Dave Croyle (Article and Photos)

Sunshield on M49

Having acquired several USGI M49 spotting scopes, I became curious as to what methods might work to reduce the possibility of glint from the objective lens. In a tactical environment, glint is one of many things that fall into the broad category of target indicators. Your opponent will be looking (and listening, and maybe even feeling or sniffing) for any target indicators that betray your presence and give him something to shoot at. While the legendary duel of Zaitsev vs. Konig at Stalingrad may be apocryphal, there are plenty of other historical examples and there is no question that glint can get you KIA.

The Butler Creek flip-up covers with their Sunshield(tm) system immediately came to mind for several reasons. First off, one of my M49s was missing its screw-on eyepiece cover, as well as the screw-in objective cover. Second, I was not particularly thrilled with the idea of a screw-in sunshade, even if I could find one to fit the M49. It wouldn't solve the problem of protecting the lenses very well, and the additional length was something I would rather avoid. With the Butler Creek covers, I was reasonably sure the scope would still fit in the M164 carrying case and the lenses could be protected.

The Sunshield(tm) system is based on the Tenebraex Corporation's killFlash Anti-Reflection Devices or ARDs. In this form, the ARDs are a resin-reinforced Nomex honeycomb inside an aluminum tube several inches long in the spotting scope version (74mm or almost 3" for the M144 spotting scope.) This is said to be the equivalent of a traditional sunshade tube 35" long. One side threads into the objective side of the scope where a rubber O-ring seal keeps out water and such, and in the case of the M144's ARD (NSN 6650-01-456-4526) they also have threads on the opposite site for use with Laser Filter Units (LFUs.)* This ARD uses a leashed rubber cap as a cover, and the honeycomb is coated with a glare-reducing matte black finish.

Unfortunately, Tenabraex does not make a unit that fits the M49 (although they are considering it.)

The Butler Creek adaptation of the killFlash ARDs is its Sunshield system. This is a plastic honeycomb that fits inside the objective lens opening and is held in place by one of Butler Creek's conventional flip-up scope covers. The Sunshield inserts for spotting scopes are much shorter than the Tenebraex equivalents, and as such add no additional length to the scope, while the flip-up cover adds scant millimeters to the overall length. Yet the Sunshield still provides the same glint protection as a 7.5" sunshade, which should effectively remove all glint and some glare. The honeycomb filters do cut down on light transmission, generally a Bad Thing, although the reduction is said to be about 15%. I am not able to determine the exact amount since I don't have the proper equipment to determine exact figures.

Being plastic, all of the Butler Creek parts add negligible weight to the scope. If used to replace the issue components, a slight weight reduction, again negligible, should be realized.

Initially with help from Duty Roster reader "Maxx" but later using the sizing chart in a catalog, I was able to determine which Butler Creek flip-up cover to buy for use with an M49's objective side, a 48 OBJ. Things were a little more complicated on the eyepiece side, however. The M49 and accessories (M15 tripod, M42A1 tripod case and M164 scope case) have been manufactured by several companies over the decades, in slightly different forms. I found that my oldest M49 (brass ID plate) had a slightly wider circumference on the eyepiece than the newer models, probably due to it having larger finger-grip ridges. In the end I determined that the older model used a 14 EYE size while the newer used a 13 EYE size. If you are considering the purchase of one of these caps, be sure to carefully size your eyepiece.

The eyepiece on one of my scopes moves very easily, and I discovered that the weight of the open cap was enough to rotate it out of the position I set, taking the scope out of focus, which wasn't exactly helpful. This was not an issue with my other M49s.

The regular 48 OBJ objective cover works great. When I purchased these flip-up covers, I discovered that Butler Creek offers the Sunshield filter in combination with an objective cover, which is cheaper than purchasing them as stand-alone items. The set is apparently supposed to fit a size 45 OBJ or 48 OBJ. In reality, both the filter and the objective cover seem to be of the smaller 45 OBJ size. The plastic material the objective is made out of stretches to fit over the M49, but not without a lot of effort. Because of this, I would avoid buying the set and get the filter and the objective cover separately, even if they cost a little more.

Since the filter is a disc-shaped piece of plastic and does not stretch, this is either a "fits" or "doesn't fit" situation. In the case of the M49, the filter doesn't really fit. It goes in easily but then rattles around inside. This is completely unacceptable if left as is. However, if you can get it to stay in place, it functions as it should. I solved this problem with some silicon rubber, which holds the filter in place, but the filter and silicon can still be removed at any time. I do not consider this an ideal situation by any means, so caveat emptor. As mine is set up, it works fine now but it took some effort to get it just right. Bear in mind that this filter is not made specifically for the M49, so this isn't a problem that should be blamed on Butler Creek.

Once the flip-up covers are in place, things are looking good. The scope still fits in its carrying case with the covers in place, albeit slightly tighter. The flip-up covers are much faster to get out of the way than the screw-on issue ones, and they are quieter too - if left untreated, the aluminum threads on the issue caps tend to squeak and screech as you are taking the covers on and off of the scope.

The objective cover should certainly be camouflaged if field use is anticipated. Otherwise, when the cover is open you have a large (2.5" diameter) black circle as seen directly by your target, which to say the least is another of those pesky target indicators. Care should be taken when painting the flip-up covers. Make sure they are OFF the scope (!!!!), and if you degrease them prior to painting (a good idea) make sure that your degreasing agent doesn't have an adverse impact on the plastic. I also successfully painted the filter, which really makes it an even greater improvement over the bare, reflective objective lens! This might make the glare reduction less efficient, but I wasn't concerned with that. Go easy and paint carefully if you try this, and remember that I won't be replacing your filter for you if you muck it up. But I didn't have any problems.

Daytime without Sunshield Daytime with Sunshield
The images above were taken in quick succession. The photo on the left is a normal image from my 35mm camera (50mm lens), and the image on the right was taken with the Sunshield over the lens. This isn't exactly scientific because your eye doesn't work exactly like a camera, but it does give you some idea about what the image degradation is on a bright day. The image taken with the sunshield is a little darker and a little grainier. The grainy effect is replaced with a blurry effect when viewed with regular eyesight. The effect also appears greater than what you see here. Note that you can actually see a few small portions better in the right-hand image because of the glare reduction.

This is a picture taken at night of a building that has several lights on around the outside. Photo was taken without the Sunshield in place.
Night without Sunshield
Picture taken immediately after, but with the Sunshield in place. BIG difference, eh?
Night with Sunshield

I used one of the M49s with the filter and flip-up covers in place on my local range last weekend, and experienced no difficulties or irregularities. When viewed side-by-side with an unfiltered M49, the image in the filtered scope is clearly a little darker but not a whole lot. (This was during the day - you can see how much more of an effect there is in a low light setting from the pictures above.) A potentially bigger problem was the "fuzzing" of the image on the filtered scope. At first I thought I had exhaled near the eyepiece and fogged it slightly, but I hadn't. The filter just made it look like I had. Bear in mind that this is with my painted filter and also with two different M49s, so telling you that this wasn't scientific and that "your mileage may vary" should be unecessary, right? Right.

What it comes down to is a judgement call. Do the advantages (reduced glint, reduced glare, better camo) outweigh the disadvantages (extra cost, reduced light transmission, slight blurring)? You'll have to make that call for your own situation. Personally, I like having the Sunshield around, and I can simply choose whether to use it or not. This would particularly be true on scopes where the Sunshield and cover really fit properly.

I ordered the Butler Creek flip-up covers and their Sunshield system from Natchez Shooters Supply, who (not atypically) had the best prices of the outfits I checked. (I always recommend that buyers shop around before purchasing, prices really vary out there!) When I ordered these last December, the eyepiece covers cost me $5.68 each, the objective cover was $5.86, and the objective cover/Sunshield filter set was $19.94. Of course, the prices could be different when you place your order, you know how that goes. As a reminder, I would recommend getting the filter and objective cover separately if you're buying them for your M49, so that you get the proper cover size.


(* US Army snipers needing an LFU for the M24 sniper rifle can get the external mount assembly (laser filters), NSN 1240-01-380-6326. The first assembly is free, along with the change to TM 9-1005-306-10 that explains their installation and storage. Contact your logistics assistance representative.)


Butler Creek
290 Arden Drive
Belgrade, MT 59714
(406)388-1356
(406)388-7204 FAX
(useless, also no response to my email inquiry)

Tenebraex Corporation
326 A Street
Boston, MA 02210
(617)574-9900
(617)574-9998 FAX
sales@camouflage.com

Natchez Shooters Supply
PO Box 22247
Chattanooga TN 37422
(800)251-7839 (Orders ONLY)
(423)899-0499 (Inquiries and export customers)
(423)892-4482 FAX

How the filter works (on the Tenebraex website)


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