5.56 Timeline

Understanding the USMC new ACOG reticle

The Marines started using a new ACOG reticle in the Squad Day Optic (SDO) on the M249 Squad Automatic Weapon (SAW). That optic got moved to the M27 IAR when the USMC switched over, and now the Corps is having the 4X Rifle Combat Optics (RCO) scopes get this reticle.

Simple, right? Pretty much self explanatory. I feel like I would be insulting your intelligence to explain how to use it.

But, just in case you weren’t clear how to use it, I’ll explain.

First, back ground info:
M249 SAW has been available in various barrel lengths. I’ve seen different numbers thrown around, but 16.3 and 20.5 inches seem to be the official lengths.
The M4 and M4A1 has a 14.5 inch barrel, and the M16 series of rifles has a 20 inch barrel.
M27 IAR has a 16.5 inch barrel.

Previously the USMC fielded two different ACOGs, the TA31RCO-A4 (AN/PVQ-31A) and TA31RCO-M4 (AN/PVQ-31B) for the 20 inch rifle and 14.5 inch barreled carbine respectively.

There is a rumor that Trijicon used the same BDC in each scope, but I don’t believe that. I do know that back in 06-07ish, higher ups in the USMC claimed that the scopes were interchangeable. I think that it shows that the level of precision considered acceptable by the USMC allowed either scope to be used.

The SDO optic, adopted for the SAW, needed to be able to work for either barrel length. It used this reticle with green illumination.

Blah blah blah, let us talk about this reticle. I could type up an explanation, but it would be easier for me to copy and past from the USMC own Squad Weapons manual.

First Zeroing:

Ideally you zero at 300m using the tip of the post. If not that, then use the top of the dot at 100m. Reduced range zeroing can be done using the tip of the post at 33m/36 yards for the M16.

Unlike the RCO models which had a Chevron and Bullet Drop Chart (BDC) that went out to 800m, these have a BDC that goes out to 1000m.

Note the narrower lines below the marked lines. We will come back to that in a moment. Those are important.

Ater the 500m line, instead of using a line to cover your target to estimate range, the SDO reticle has a gap. You fit the torso of your target into these gaps to find the distance to them when you are using the 600-1000m section of the reticle.

What are all these smaller lines below the BDC range lines?

As previously explained, we have these 14.5-16.6 inch barreled guns, and 20-20.5 inch barreled guns. The lower smaller line is for the ballistics of the shorter barrel.

This scope had a BDC for the rifle and the carbine (or the Para-SAW and the standard SAW). This lets the USMC have a single ACOG that can work on the M4/M4A1, M16A4, M249 (regardless of configuration), and the M27 IAR.

I’ve shot out to 1000 yards (~914m) with an ACOG and it is far from ideal for that job. But it is far better than using iron sights at that range. While stuffing a 1000m BDC in an ACOG may be idealistic for the one shot one kill rifleman, it very useful tool for the automatic rifleman’s suppressive fire. It is better for our troops to have it and not need it, than the other way round.

How the Israeli’s use the TA31i ACOG

Previously I wrote about the TA31i ACOG that the Israeli’s use:

Quick recap, it is a 4x ACOG with a different reticle than the normal fare.

I was really curious about the markings and zeroing on this model ACOG. Recently I learned about how it was used.

Their TA31i ACOGs were mounted on ARMS quick detach mounts. This allowed them to switch between the ACOG and a night vision scope. The intent is that the night vision scope could be used at night out to 300m, and the ACOG as a day/night optic out to 500m.

The Israeli’s use a 250m zero on their rifles. They sight in 4 cm low at 25 meters using 62 grain ammo. This is suppose to give the following ballistics:

Distance (m)Drop (cm)

I was playing around the numbers in JBM ballistics and I am unable to recreate this reported trajectory.

There are pictures out there of this optic being use on rifles with 11.5, 13, 14.5, 16, and 20 inch barrels. Sometimes the optic is mounted on a flat top. Some times it is mounted on a rail installed on a carry handle. I wanted to find and post up some of these old pictures. But unfortunately I did not save a copy to my computer, and I think they were hosted on photobucket or tinypic or the like. They appear to be gone.

When I plug numbers in JBM ballistics, using 4 cm low at 25m on a M4 firing M855 would have the impacts constantly low. I just can’t see how these numbers work. I wonder if this was calculated from when the IDF was using 13 inch barreled rifles with carry handles.

Anyways, back to the topic at hand. Let us look at that reticle again:

The IDF designated marksman, sharing his notes, explains that the vertical lines on the far left and right of the reticle are for range finding using the size of a human head. The two longer vertical lines are the height of a human head at 200m. The shorter line is the height of a head at 300m.

They continue to explain that the width of the line between the two longer vertical lines on each side represents the shoulder width (commonly 19-20 inches) of a man at 400m.

The line between the shorter vertical line and the longer vertical line on the end is that shoulder width at 500 meters.

Now on a normal ACOG, the lines in the bullet drop chart represent a 19 inch wide width at the respective range in meters. This Israeli marksman was taught that on the TA31i ACOG that these lines represent the length from a persons back to chest (if they were facing perpendicular to you). So you have two ways to range a torso at 400 and 500m and a way to find the range if you can see the targets head at 200 and 300m.

I have a good many mixed thoughts about this information. No offense to the marksman who provided this information, but the trajectory numbers seem questionable to me.

In one way, I really like how you can range a head at 200-300m with out pointing the gun directly at the person. If you had their head lined up with one of those left or right ranging lines, the muzzle will be pointing a fair distance away from the individual.

When using this scope, I found I really liked having the horizontal line as it felt like it increased speed and ease of use. But I missed having a defined aiming point for 100m.

Sopakco repack “MRE”s were not what I expected.

I picked up some cases of Sopakco’s MREs. I’m not overly thrilled with them. They are repacks, and were $2.50 each shipped.

Now I am fine with repacks, but they changed the nutritional content of these. The Meals Ready to Eat (MRE) in the military are about 1200 calories and contain a main meal, side dish, snack, beverage mix, along with a heater and accessory pack. The accessory pack would have a spoon, toilet paper, matches, coffee mix, creamer powder, salt, sugar, red pepper or Tabasco sauce, a moist towelette, and gum.

These Sopakco “MRE” packages contain a main meal, heater, crackers, 2 jellies or jams, a toaster pastry, and candy along with a packaged spoon with napkin and salt and pepper. These meals run about 1000 calories, and much of that comes from the candy and sugar packed jams and jellies.

For $2.50 each, the Sopakco MRE is not a bad deal. But these meal combinations are far from the “fortified with nutrients” balanced meals of a full and proper MRE.

Lastly, and possibly most annoying, is that the cases are not proper menus. I saw a review on Amazon where someone claimed that they received a box where the entire box of 14 meals were all the same meal. Others reported getting 3-6 of the same meal in a box.

Colt SCW Stock Set

 Guest Post by Brent Sauer

          This article is intended to be about the very unique Colt Sub-Compact Weapon (SCW) stock set. However, we can’t talk about the SCW stock set without briefly talking about the background story of the SCW weapon itself.   

          Around 2005, the idea for the Colt Sub-Compact Weapon (SCW) was born when the law enforcement community asked for a weapon that was compact enough to fit in a motorcycle officers cargo saddlebag. Although the weapon was initially designed for motorcycle mounted officers, it quickly became apparent that the SCW would be a versatile weapon for use by security or military personnel in vehicles and in Close-Quarter Battle (CQB) roles also.

          After the design and testing cycle was completed, the SCW made its first public appearance at the 2008 Association of the United States Army (AUSA) show. This appearance got the weapon system noticed by some potential foreign customers. Israel adopted the SCW for their special forces and adoption by Mexico soon followed.

          The SCW was designed as a 5.56mm weapon and had a 10.3” barrel. The requirement was for the new weapon to give a responding officer rapidly deployable firepower greater than the service pistol that was carried. Initially fielded as a select fire weapon, it was also sold in semi-automatic only variants. What really made the design of the SCW stand out was its unique stock that folded in two places and could be extended/collapsed. The receiver extension design along with the unique bolt carrier/buffer assembly enabled the weapon to be fired with the stock folded or extended.

          The SCW stock kit consists of the following components:

1. Shortened Full-Auto Bolt Carrier Assembly

2. Receiver Extension

3. Buffer Spring

4. Receiver Extension Nut

5. End Plate

6. Collapsible/Folding Stock Assembly

7. Buffer (tungsten and steel construction just like other buffers)

          The stock body is hinged at the back of the receiver extension and folds 180 degrees to the left side of the weapon. When folded, the stock is parallel to the receiver. There is a detent that locks the stock in the folded position. In addition to the stock body folding, the butt of the stock folds under, and up at 90 degrees bringing the butt of the stock parallel with the stock comb.

          Another standout feature of the SCW stock kit is the unique buffer design. It is about a half of the length of a traditional carbine ‘H’ buffer. However, it has the same weight of an ‘H’ buffer at 3.6 ounces. The buffer actually ‘keys’ into the back of the bolt carrier about a quarter of an inch instead of the bolt carrier impacting the face of the buffer. During the firing cycle, the bolt carrier and the buffer move as a unit. This operating design eliminates the use of a buffer retainer in the SCW carbine.

          The complexity of the Colt SCW stock ended up being its undoing. In hard use the stocks were somewhat fragile. There were a lot of small parts used in production in addition to the molded plastic stock parts. Assembly of the SCW stock in the factory took a long time and was so complicated that Colt struggled to have an efficient assembly process for the stocks which hurt production forecasting and scheduling.

          In 2016/2017 Colt stopped using their proprietary SCW stock and changed to the Maxim Defense CQB stock for their SCW weapon. In an effort to clear out leftover inventory in the factory, Colt sold 11 remaining stock kits to Arms Unlimited. On 10 July 2017 Arms Unlimited made the stock kits available on their website for $800.00. After a couple of stock kits were not paid for by customers, the price went up to $1200.00 and those remaining stock kits were relisted on the website and quickly sold. Here is a look at the final site listing: https://www.armsunlimited.com/Colt-SCW-AR15-M4-Folding-Stock-Assembly-Kit-p/scw0921ck.htm

          Needless to say, these stocks are a rarity on the collector’s market. I know where four of them are, with my stock that is shown being one of them. I paid $1200 for my stock (with a broken folding lock detent) and was just glad to have the opportunity to get it. I have only seen one SCW carbine for sale and it is sitting on Gunbroker right now for $9995.00. It is supposedly one of only five SCW carbines that entered into the civilian market.

          Although many critics of Colt in the firearms community accuse Colt of not being innovative, you don’t have to look very hard to find innovative work that Colt has done. The SCW carbine, and the SCW stock set, is just one example.

Colt SCW with Maxim Defense CQB Stock

30 years of the Eagle A-III pack.

I mean, it has been around for 30 years, I’ve only had mine for 13 years.

I hate this pack. But that is just me, ignore that.

When I was in Iraq, back in 2006, I was my platoon’s radio operation. I don’t think my higher ups liked me much, so I got that job. Carrying that AN/PRC-117F really sucked. I kept looking for a better way or back to carry it as it made my back and knees hurt packing the radio along with all my other gear, and the radio support gear. One of the several packs I got during that time was an Eagle A-III airborne pack.

There is some debate if the Eagle A-III was a copy of some other design, but it was one of the early purpose made tactical packs that was greatly copied by other companies in and out of the tactical community. There were many versions of this pack. Some where slick, some had ALICE webbing, some had MOLLE webbing, other has purpose made pouches. Blackhawk copied and and made it overseas cheaply flooding the market. I think that lead to Eagle discontinuing it. John Carver, designer of the A-III, now has a company called Atlas46 which makes new production “A3 Legacy Pack”.

The basic A-III pack pretty much look like any other modern backpack. But back when it came out, having a smaller pack that was completely subdued was a pretty nice option. I wanted to buy one covered with MOLLE webbing, so I could slap on what ever pouches I wanted for the mission I was doing.

The picture above is what I wanted to buy. But, that was unavailable. So I had to settle with the airborne model. Part of me loves the idea of having a jumpable pack. But, for it to be jumpable, it has tons of extra straps and stuff sown on it.

All that extra strapping for airborne ops adds weight and bulk.

Most annoying for me, was that the airborne model had pockets sown on the sides. On one side there was a small general purpose pouch. On the other a radio pouch and a pouch about the right side for 2 M16 magazines. I used these to carry extra AA, CR123, and those big BA5-something or another batteries.

One of the big selling points of this pack, back in the day, was that you could open the main compartment completely. That was pretty rare 30 years ago. Inside the A-III pack, there were often cinch down straps for securing what was inside the pack. There are all manner of customer A-III, some with pre-segmented main compartments. For example there was a medic’s version of the pack organized for medical gear.

Each side of the top of the pack has a hook and loop secured flap covering an opening. These two opening would corespond to the antenna and the microphone of a AN/PRC-117F radio. They could also be used for a hydration pouch, or similar. This pack has an area for a hydration pouch, but does not include one.

They sold a stiffener you could purchase and place in that area to give the pack additional rigidity. This had a strip of vertical alumnium in. It did sorta work, but wasn’t worth the cost.

The bottom of the airborne pack has some of the normal webbing, along with a weird set of velcro covered flaps. I’ve been told that the idea was that you could put a pop flare in there, and easily grab it with either hand when wearing the pack. I tried putting a M127A1 Parachute flare there once. Not a practical place for it. Also I didn’t like that when I took the pack off and set it on the ground it would be sitting on the flare.

It comes with a couple extra straps so you could strap gear to the outside. For example you could use them to strap a sleeping bag or mat to the bottom of the pack. It also has a waist band. I removed mine, and found it the other day which caused me to dig up this old pack from storage. Now that I have the pack out, I can’t find the waist strap. It was generic and padded, nothing special.

Between the main compartment, and the two other compartments on the body of the pack, the A-III had plenty of storage space. It seems now that we tend to use either much smaller packs, or much larger packs. Even so, there are many A-III packs and knock offs out there still being put to use.

But not mine, I hate this thing. It wasn’t the model I wanted, and it reminds me of a job I hated.