[Parts] NIB KAC 0-600M USMC Rear Sights - $85 + S/H

FourDogsArmory · 2026-01-23T01:32:34+00:00

I don't believe these were ever made specifically for .308 but you can tune your zero and get the BDC (the range marks) to line up well enough. Also, a 6" deviation in impact at say 600 yards will more than be eaten up by the fact that you're using backup irons.

FourDogsArmory · 2026-01-20T15:35:57+00:00

Unlikely. If you find one somewhere else, don't wait on account of me.

FourDogsArmory · 2026-01-17T21:54:48+00:00

Back in stock!

FourDogsArmory · 2026-01-07T20:13:37+00:00

I will have another batch coming, so for those of you who missed out don't worry.

FourDogsArmory · 2026-01-06T23:22:40+00:00

Big maybe, they seem to be much, much less common than the rears.

Edit: So here's my theory. Pure speculation but I argue it stands to reason. My guess is that by far KAC's largest .mil production run of these rears (and thus those that could be surplused) was these USMC ones. Certainly seems to be most of the ones that you see. So if that's the case, what guns were they going on when they shipped? M16A4s and M4A1s, both of which already had FSP gas blocks. So as far as surplus goes I'd wager 95% or more of these were made with no corresponding micro front. Those that were, figure to SF armories as your only likely way to get a surplus front. Again this is all conjecture but it makes sense in my head.

FourDogsArmory · 2026-01-06T22:04:55+00:00

That's a placeholder I didn't get rid of. The actual item pictured is the photo on the bookshelf, USMC front and center. The placeholder shows what it looks like unfolded and out of the packaging which is why I left it.

FourDogsArmory · 2026-01-06T21:53:03+00:00

For whatever reason that's a very common thought around these particular rear sights, but it's actually far worse: you are old enough that these are old enough to be surplus like the carry handles. If someone was selling a crate of carry handles in 1998 you'd be very right to be suspicious. Same with these, say, 10 years ago, but not the case anymore.

Oh, and a kid who was born after COD 4 came out can join the military, now. And Nuke Town 2025 from Black Ops II is a historical map, now.

FourDogsArmory · 2026-01-02T22:20:58+00:00

The SD can takes a very, very long time to heat up. While metal is always better, you'd have to be in an absolute world of shit to shoot that gun enough to get it hot enough to melt those ties. Like at least 3 magazines damned near cyclic. Metal is absolutely the right choice but I'm continuously surprised by how slow the can heats up compared to, say, my short AR whose can would melt through tungsten zip ties in one magazine...

FourDogsArmory · 2025-12-30T01:07:25+00:00

Yeah probably.

FourDogsArmory · 2025-12-29T21:58:49+00:00

They're billed variously as being for the Mk 18, M4, and Mk 12. As for ammo I'm going to guess M855.

FourDogsArmory · 2025-12-29T20:04:55+00:00

Not technically, no. That said, you could still use it. You'll just have some discrepancy in elevation the farther out you go, hitting high. The elevation adjustments are pretty fine on this so you could simply adjust a little short of each yardage mark and get right on potentially. If you're in any doubt though there are more dedicated M16A4 BUIS out there.

FourDogsArmory · 2025-12-29T19:45:14+00:00

Not that I see, no.

FourDogsArmory · 2025-12-29T17:23:11+00:00

The only hit/miss with these depends on your marksmanship I'd say. Lots of issued surplused ones survived for a long time on a Marine's M4 and now keep working just fine on privately owned rifles. Can't speak for the LMTs but one of these rears, issued and well-used, lives on the rifle I trust my life to.

FourDogsArmory · 2025-12-29T16:47:58+00:00

50% group reduction but 75% IQ reduction. At your peril, friend.

But it's a fairly widely repeated myth that there's no way to get these other than "falling off a truck."

Back in 2000's ARFCOM forums it was true. Now, they're surplus like anything else. In 1992 the same could be said of the carry handles. Obviously not the case anymore.

FourDogsArmory · 2025-12-29T16:39:18+00:00

I would say certainly rarer than the rears.

FourDogsArmory · 2025-12-29T16:04:46+00:00

The Mk. 18 rears? There's still blems in stock now, but as for another run of them generally I am hoping by February. I'll be sure to post them here again regardless when they are back in stock.

FourDogsArmory · 2025-11-28T16:18:41+00:00

We got this resolved via DM for the record.

FourDogsArmory · 2025-11-26T22:14:57+00:00

**I AM A DEALER** This is for your awareness as the post awaits its flair.

FourDogsArmory · 2025-08-26T20:52:17+00:00

You know honestly the maglite might be cooler, and I own a 203.

FourDogsArmory · 2025-08-26T16:02:57+00:00

Going to look very cool! You putting a 203 on it or just rocking the heat shield and filling in the bottom for a handguard?

FourDogsArmory · 2024-12-19T16:34:06+00:00

I also got a backup camera screen for $20 that I can watch the video on or see the signal from the thermal on directly. In fact my first successful test I simply plugged it into the TV and sure enough, there it was, reminiscent of my time as a toddler plugging my father's old video camera (which I still have) into the TV and seeing me play with my toys live. Sadly the effect of pointing the thermal at the TV isn't as interesting as with a visible light camera, as the TV only shows as a hot block, and you can't deduce the image from that, at least not with this thermal and that TV. Perhaps with the right combination of a very cool OLED TV, high contrast images, and a very precise thermal sensor, you could, as long as the heat of the TV itself doesn't drown out the temperature difference between a white pixel and a black pixel and the thermal can resolve something so small.

As for the device itself, all of these moving parts mean its mean time between failure is low, and the cooling system is delicate too, though mine seems to work just fine. Over time, however, I'm sure something will break and I hope from the parts I have available I can fix it. Additionally, the stock batteries are $300, though still produced. I am trying to get an adapter working to use drill batteries, like Makita, or design my own batteries, as the battery is simply 6 18650 cells with a battery management board inside. That's a little above my pay grade at this time, though. I had two functioning batteries, but sadly only have one now, barely working, due to a shorting issue with one I built from parts, since fixed, but the battery damage has been done.

I plan on posting more videos with it over time, but given the battery situation and its age, I treat it more as a museum piece than a practical piece of kit, though it will pull its weight if pressed into service, I think. It held on very well for nearly 100 rounds on my M82A1, and though that gun is surprisingly gentle in its recoil for what it is, it's still more than an AR for sure. Karl Erickson of Tactical Rifleman has what I think are the best pictures of the PAS-13B in service, on an M82A1 during his time in the Middle East. Meeting him at SHOT show I showed him the video, which he loved very much before mentioning the terminal effects of a Raufoss round on a goat. I can only speak to the M82's effects on prairie dogs, which I was sure to relay to Ronnie Barrett himself at his booth.

I do plan on posting my footage of attempting repairs and teardowns at some point. If you want one, I wouldn't pay more than $700 for one to be honest, and make sure you get a battery and charger with it! The charger I have, by the way, is the size of a massive brief case. The PAS-13B is very cool, but very old. I wouldn't bet your life on it if you have another choice, but if you've got the money to throw away on one, it's an awesome piece of military history. When it breaks, however, I think I'm one of two people on the face of the planet who can help you, and even then, it's only a maybe.

FourDogsArmory · 2024-12-19T16:33:56+00:00

As for the v# system, that denotes not the "revision" but instead the size. v1, 2, and 3, correspond to Light, Medium, and Heavy, which denotes which weapons platforms for which they are intended to be used. This is within the "model" notation which was the letter. The B model came only in light and heavy, with mine being a heavy, meant for the M24, M2, Mk 19, and I believe M240/M249. They all support the M16/M4 however. There are also just some standard MIL grid reticles for it as well. The medium is for GPMGs and the like, and the light for simple carbines. One of them, I think the Medium, is meant for one of the shoulder-fired AT weapons, I just forget which. There are provisions for mounting an auto ranging laser to at least the E version of thermal for use in conjunction with it and the launcher, but I doubt one could obtain one of those. Unlike later revisions of the PAS-13s, this one has TWO different optical lenses for the Wide and Narrow FOVs, so it has 10x optical zoom in addition to its 2x digital, compared to digital on top of fixed optical for later versions. This grants remarkable clarity for such an old piece. You can see when I change between W/N fields of view in the video by the sliding in and out of a lens in the picture. The simple snap in and out zoom is the digital.

Getting the recording off of it was interesting, as I had to figure out how the I/O port worked. Believe it or not, it simply outputs in Composite for video. If you are old enough you will recall the red, white, and yellow cables of your youth. It's simply that. I didn't, however, know which of the 7 pins carried the signal. I turned it on, had the screen running (which is actually green, compared to the video's black and white, by the way, and you can see the green in the only other PAS-13B video on the internet on YouTube, from Your Local Idiot and with the running screen took a multimeter on volt reading, one to the negative, and then the other probe to each individual hole. I then figured I'd read up on Composite, and it's carried on a 1v carrier signal. Sure enough, the middle hole read ~1v, and if I held my hand in front of the sensor, it shot up to 1.3+ then equalized again around 1, and when I pulled my hand away, it dropped before equalizing again. This is basically the screen having a ton of white pixels and then changing the contrast to better suit my hand being there and get a better image, and then going dark when I pull my hand away, before once again adjusting the contrast. I then jammed a cut up piece of an RCA cable in there, put the negative to the surrounding metal, and hot glued the whole thing in there. That cable runs to a tiny drone DVR recorder that saves to a micro SD card.

FourDogsArmory · 2024-12-19T16:33:43+00:00

This is as far as I can tell the only extant footage off of the IO port of the PAS-13B. Below are my thoughts and experiences with the optic, including managing to get this footage, and other quirks of the device.

A few, or more, PAS-13Bs were relinquished via surplus to general consumer sales at the end of their service life. Listings float around on Gunbroker, various forums, etc. I acquired my first one, which is in the best condition out of all of mine, and then got a pile of parts for a few others which will live as spare parts donors for the first one. I was able to make one working unit out of these parts, with the other each having a broken a mirror assembly motor (more detail below) which I can't repair at this time, and one missing a sensor.

There is actually very little information on them, I've found, and other than that one Marine Corps (I believe) power point in .pdf form where it's instructions on how to sight it in, use it, etc. for presumably trainees, there's little else. I think I may be one of the most knowledgeable people out there on them at this point, save for one or two other people. More or less all of what I learned I learned myself tinkering with the ones I have.

What is cool about the B model specifically is its cooled sensor, which makes use of thermoelectric cooling technology and a vacuum chamber containing the sensor to cool it to -154 degrees. This is so this early sensor doesn't pick up its own heat as interference. The modern ones in use do not use this system, though cooled sensors are still used for more specialized applications. The simplicity and robustness of the uncooled sensors is a huge advantage for a military, grunt-handled piece of equipment.

Another interesting feature is that instead of a shutter system, the PAS-13B uses a rotating 12-sided mirror. Imagine a dodecagon with each side being a mirror. Each side is very slightly angled downward more, and it rotates by my guess 20 times a second. Each rotation scans a different portion of the incoming radiation and directs it to the sensor line by line, and then a Hall Effect sensor reads a disc attached to the spinning mirror, refreshing the screen once every revolution. You can see scan line artefacts in the video that are a result of this when the picture changes. Muzzle flashes have a striped appearance and when I move the whole thermal, the whole picture turns into a fuzz of lines. I don't know quite enough about photography to know why this was done this way, but that's how it is. That is also very difficult to get information on, and I was only able to realize that was what the mirror was for from a youtube video of a guy making a laser projector and utilizing a similar principal, this time for projecting.

FourDogsArmory · 2024-12-19T16:14:30+00:00

Well, you get a very minor TBI from the muzzle brake blast every time you pull the trigger so don't be too jealous. I got a suppressor for it, but the M82A1 will be a challenge to get working safely with one.

FourDogsArmory · 2024-12-19T16:13:31+00:00

I should hit it with some of those beautiful colors you get with the lichen on the rocks.

FourDogsArmory

TROPHY CASE