November 2001

Light & Lighter: The Carbon 15 Packs A Wallop Without Heft

At 4.3 pounds, Professional Ordnanceís Carbon 15 is the lightest AR15, and itís a very good one. Bushmasterís lightest rifle, the XM15-E2S, is also worth a close look.

Tech Editor Ray Ordorica declared that if he
wanted an AR-15-type rifle, he would choose
the Carbon 15 Model 97S shown. This was a
popular rifle with our testers.

In the June 2001 issue of Gun Tests, we looked at three 16-inch-barrel AR-15s, and their relative lack of weight greatly appealed to us. In fact, the lightest of that trio, by American Spirit Arms, was our pick of the lot, not the least reason being its lack of tonnage.

In this report we take a look at the lightest, complete, iron-sighted, AR-15 existent, the Carbon 15 Model 97S by Professional Ordnance Co., which uses composite construction to achieve an empty weight, without sling or QD compensator, of only 4.32 pounds. Because that rifle had a slightly unconventional takedown, we also looked at another model from the same company which takes down just like every other AR-15/M16 in the world, the Model 97SF. It was a pound heavier than the Carbon 15, but some conservative shooters may prefer it for its familiar takedown procedure.

We also examined a very light all-metal offering from Bushmaster, the XM15-E2S Super-Light Carbine. At 6.7 pounds it was lighter than most AR-15s, though way heavier than the Professional Ordnance rifles. Here are our findings.

Professional Ordnance, Inc., Carbon 15, Model 97S, $1,285
Before we opened the shipping box we knew we were onto something. The entire box—carton, shipping materials and all—weighed noticeably less than any other AR15 we’ve handled. On opening the box we found an innovative and attractive rifle complete with sling, muzzle brake, and 30-round Thermold plastic magazine (optional, while supplies last). It had a near-unbelievable feathery feel. We’ve seen heavier BB guns. The upper and lower portions of the action, the butt stock, forend and top rail were, as the rifle’s name indicates, made of a composite material consisting of polymer with carbon-fiber reinforcement — just like the chassis of a Formula One race car.

Click here to view the Professional Ordnance, Inc., Carbon 15, Model 97S features guide

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The sling was attached via Velcro strapping on both the forend-encircling portion, and at the extreme rear of the stock. More than just a Velcro strap at the attach points, the sling went through a buckle and back onto itself, so retention was extremely positive, yet the sling was readily removable. It required a knack to get the sling off the forend, but once learned, it was easy. The nylon sling was called “silent,” and that was a good name for it. It made no sound whatsoever. It could be configured in a variety of ways to make carry and deployment of the rifle very easy.

The Carbon 15 was light but very well balanced, with most of the weight between the hands. It was entirely matte black except for the stainless barrel, which was left white. The rear sight was essentially mil-spec, consisting of two rear apertures, large and small. This sight was attached to a set of ears that were formed into the top rail out of composite material.

The rear sight was adjustable for windage by a thumb screw. The flat-top square-post front sight, which gave an excellent sight picture, provided elevation adjustment through the fact that it was a screw with a spring-loaded detent.

The 16-inch fluted barrel had a clever removable muzzle brake. Much post-shooting crud can develop over time inside a brake, and the crud can harm accuracy if it’s not cleaned out, so Pro Ord made this brake removable. The brake came off so easily as to be unbelievable, and went back on in the same manner. Following the directions, we pulled forward on a spring-loaded sleeve, gave the brake a slight twist, and off it came. Inspection revealed three balls within the brake that fit into three machined dents or depressions in the barrel around the muzzle. The balls were forced into the dents by the spring-loaded sleeve. To reinstall the brake we pushed it onto the barrel while holding the sleeve forward, then released the sleeve. We twisted the brake slightly to align the gas-port slots in the vertical position, and the sleeve snapped back into place to retain the brake. There are also other muzzle-attaching options available in place of the brake, such as threaded adapters for a variety of muzzle-altering devices such as compensators, when such are both legal and desirable.

The match-grade barrel was of stainless steel, which made it rust-proof and easy to clean. It had 1:9-inch twist, and six rifling grooves. The external barrel flutes were square-bottomed, and the overall look was thoroughly business-like. Pro Ord has available numerous flashlight or laser mounts that attach to the barrel between the brake and forend.

The forend was a large plastic-composite oval. This fore-grip, as Professional Ordnance calls it, was insulated with a ceramic-fiber inner wrap, so the supporting hand wouldn’t suffer from hot barrels. That’s a very important consideration when you realize this rifle is also made in a fully-auto configuration. Yes, carbon-fiber-reinforced actions hold up very nicely to full-auto operation, or so we have been informed by those who have fired them extensively.

The overall configuration of the action was essentially identical with mil-spec actions, and included a brass-deflecting (removable) hump behind the ejection port. There was no forward assist, which in our tests have proven to be questionable accessories anyway, though some like ‘em. Another limitation of this particular composite construction was that the bottom of the trigger guard could not be opened for winter use with gloves or mittens.

The trigger pull was very good. It broke with minimal creep at 5.5 pounds with negligible over-travel, and was very controllable. We have come to like good triggers on AR-15s, and this one was very pleasant. The pistol grip was Hogue’s “OverMolded” design, with finger grooves that fit most of our hands well.

There was a buffer behind the bolt to lessen recoil. The folks at Professional Ordnance planned all this very well, because there was very little sense of recoil from the rifle. The muzzle didn’t rise (though there was a big, upward-directed ball of flame from the Russian ammo). The push on the shoulder was essentially non-existent. One could shoot this rifle all day long with no discomfort, which brings us to ask, why in heck are so many AR-15s so doggoned heavy? This one was a real sweetie in every way. Okay, some like extra weight to help hold the rifle steady. But if the rifle is very light, you won’t be out of breath from totin’ it, and will be all that much steadier without the extra weight.

Takedown was a bit odd. We first had to remove the stock, which was accomplished easily enough by turning a small plastic lever rearward and then pulling the butt stock off toward the rear. (It weighed 3.5 ounces.) We then unscrewed the cylindrical housing protruding from the rear of the action, which held the recoil spring. This was done with care to control the expanding recoil spring, but its tension was slight with the bolt in the forward position. Once the spring and the buffer were out, takedown was normal. The rear-most action pin was pushed toward the right until it stopped, and then the action broke upward, just like a normal AR15. The bolt and activating rod could then be withdrawn. Reassembly was straightforward.

With the bolt out, we first noticed it was much shorter — and lighter — than normal bolts. Also, we noticed its extractor was absolutely huge. Pro Ord claims it grabs 58-percent more of the case than normal extractors. Function and lockup of the hard-chromed bolt were strictly conventional. Fit and workmanship throughout the rifle were excellent. We were impressed with this rifle, its careful construction, and its innovative design.

One thing you won’t find on the Carbon 15 is the mil-spec, spring-loaded ejection-port cover. We didn’t miss it in our relatively sterile conditions. The bolt locked rearward after the final shot, or whenever the standard hold-open device was activated manually. The two-position safety was ambidextrous, and it worked positively and correctly, though it interfered slightly with the off-side knuckle of some of our shooters. Our lefty was gratified. The “fire” position was a bright-red F, visible on both sides of the action, with a white S for safe.

The top of the Carbon 15 held a full-length rail made in the form of a Weaver base. The base extended to the front of the forend, which would have permitted a “Scout”-type mount, with long eye relief. Some shooters find that setup extremely fast and very practical.

The iron-sight mounts, at front and back, were composite. We liked the super-light iron-sighted configuration so much we decided to not mount a scope. One thing about scope mounting is that unless you do use a “Scout” type mount, you’ll have to use very high bases because that rear sight, on this version of the Carbon 15, is there to stay. The scope eyepiece has to either be in front of it (Scout setup), or high enough to clear it. Pro Ord has versions of this rifle without iron sights to ease scope mounting, but they don’t have a full-length rail, so you’ll have to mount a scope conventionally.

At the range we found the rifle fed reliably from all magazines tried, including ordinary mil-spec units. We tested the guns with Black Hills’ 60-grain soft nose, and 68-grain hollow-point Match loads, and also with some surplus Russian ball ammo. Initially the rifle shot very low, but quick work on the front sight got us in the right spot, with plenty of adjustment on either side of zero. We had to run the rear sight almost all the way to the left, but again there was room to spare to zero the rifle.

Click here to view "Accuracy and Chronograph Data."

The Carbon 15 made a decent accuracy showing, making acceptable groups with all ammunition tried. Worst groups were with the Russian surplus ball ammo, averaging around four inches at 100 yards. Best results were with Black Hills’ 68-grain Match fodder. The best three-shot group of the test was one ragged hole at 100 yards, that we measured at a quarter inch. Average groups were well under an inch with that ammo. The mate to this rifle produced identical-range groups with all ammo tested, so we gave combined data in our accuracy results. A scope would have cut all groups slightly, but any scope would reduce the handiness of these extremely light rifles, and seem to defeat their purpose.

Carbon 15 Model 97SF, $1,185
One hundred dollars cheaper and a pound heavier, this version of the Carbon 15 had a conventional, mil-spec butt stock, which permitted normal AR-type takedown. The action was opened by first pressing the rear action pin to the right, which permitted the rifle to swing open much like a double shotgun.

Click here to view the Carbon 15 Model 97SF features guide

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Inside, we found a normal-length bolt, but it had the top-most portion of its rear surface milled away to reduce weight. Also, the bolt was blued, not hard-chromed as on the lighter version. The barrel was again stainless. This time we found two pairs of slots in the top of the forend to release heat. At no time did we feel any discomfort, or any heat whatsoever, from the non-vented forend on the first Carbon 15 tested, and wondered why the company would poke these holes there. Perhaps full-auto ops require it, but this wasn’t a fully auto rifle. Another difference was the pistol grip, which here was mil-spec configuration, not the softer Hogue. It did not have the option of opening the bottom of the trigger guard.

The trigger pull had even less creep than the other Pro Ord rifle, but it broke at 7 pounds, which was a bit too much for our tastes. It was, however, a clean break that gave us good control over the rifle.

On the range, It performed exactly like the other unit, so much so that we combined the test results. Even the chronograph readings were the same.

Most of us liked the lighter version of this rifle instead of this gun. At this level, an extra pound represented a 25-percent weight increase. As stated, there was so little felt recoil in extended bench shooting, even with the heaviest bullets, that we could not justify the extra weight of the normal mil-spec butt stock. Also, the spring within this standard-type stock made an unpleasant whanging noise in the shooter’s ear that was in startling contrast to the other version, in which the spring was silent.

Bushmaster XM15-E2S Super-Light Carbine, $1,020
Strictly conventional? Not quite. The buttstock was pseudo-collapsible, looking like the mil-spec version but, per current law, of fixed length. We’ll tell you right now we didn’t much like that buttstock. Yes, it was lighter than the normal AR-15 stock, but a ridge in its middle caught most of us on the cheek right where we laid our faces on the stock. There was a detachable carry handle that held the fully adjustable, mil-spec, two-aperture rear sight, and that handle added $90 to the Bushmaster’s price. This weapon was very similar to the “Shorty” Carbine we tested in June of this year, but its lighter stock, thinner barrel and short forend got the weight down to 6.1 pounds without sights. By comparison, the “Shorty” Carbine weighed 7.0 pounds without sights. With the carry handle attached, the weight of this Bushmaster rose to 6.7 pounds, which was our test weight. This Bushmaster also looked a lot like the American Spirit Arms Corp. Lightweight Flattop we tested in June. The Spirit weighed only 5.9 pounds without sights.

Click here to view the Bushmaster XM15-E2S Super-Light Carbine features guide

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The short, vented forend helped keep weight down, as did the thin, unfluted 16-inch barrel. However, the huge brake added 2 inches and numerous ounces to the muzzle, and looked like it could have been made lighter. More on the brake later. In most cases, the traditional AR-15 design, even on this well-done version by Bushmaster, puts needless weight on the rifle, stuff we didn’t notice until we had the Carbon 15s in hand. That doesn’t make it all bad, but once you see how light and recoil-free these little rifles can be, you’re gonna be spoiled.

Everything about the Bushmaster was matte black. It was a compact and rugged version of the “black rifle” that appealed to us far more than most all-metal versions of this rifle we’ve seen and tested over the past few years. The Bushmaster’s barrel was marked 1:9 twist, and was very slim over the visible portion. The conventional action had the forward-assist button, mil-spec grip, non-ambi safety, and yes, the bottom of the guard could be opened for winter shooting, if desired.

The top rail of the action was only as long as the action. This meant a scope had to be mounted conventionally, not scout-style. However, the rear sight would not get in the way of scope mounting, because when you take off the carry handle you lose the rear sight. Conservative shooters will want some sort of iron sight on their rifles to back up the scope, at least when rugged field use is anticipated. With the Carbon 15 rifles you couldn’t get rid of the rear sight, and that might help you decide which to buy.

Sling mounting was achieved via front and rear sling rings, one hanging from the front-sight mount and the other screwed to the bottom of the butt plate. A mil-spec sling came with the rifle along with one 10-round magazine, the lot packaged in a hard-plastic padded carry case.

The trigger pull was 7.5 pounds, without creep. We would have liked it lighter, but lived with it as it was. Workmanship of the entire rifle was, overall, excellent. We couldn’t fault the Bushmaster’s manufacture or any of its function. It did all it was supposed to do, and was as fine an all-metal version of the AR-15 we’ve seen.

On the range, we were made painfully aware of the muzzle brake from the get-go. A strong wind blew rearward with each shot, and nearly tore the tape of our recording chronograph with each shot. The noise was bad, but the wind was worse. The Carbon 15 was also loud, but we didn’t get that big-wind effect and found it much more pleasant. Felt recoil was about like that of the Carbon 15 pair, very slight. The sight pictures of all three rifles were identical, and all excellent. We used the smaller aperture on all rifles for our test shooting.

We found the Bushmaster shot both types of Black Hills ammo very well. The 60-grain soft nose gave us the smallest three-shot group, just 0.5 inch at 100 yards. This beat the best Match ammo group very slightly, and averages with the 60-grain fodder lead us to believe a bit of load development would pay immense profits with this particular rifle. As expected, we got along with its stiff trigger very well off our machine rest, but a lighter trigger pull would have been welcome. The Bushmaster Super-light didn’t like the Russian ammo all that much, giving around 5-inch averages. Can’t have everything, we guess.

Gun Tests Recommends
Professional Ordnance, Inc., Carbon 15, Model 97S, $1,285. Buy It. The Carbon 15 is, in the final analysis, a complete, ready-to-go rifle that weighs just a bit more than many pistols, yet has the ease of hitting that is inherent in a rifle. Its extremely light weight lets you pack a rifle in situations where a handgun would most likely be the first choice. If you want or need even lighter or more compact .223 firepower, the Carbon 15 is available in two simpler rifle versions, without iron sights, called the Types 97 and 21, and in two handgun versions, with 7.25-inch barrels. We believe many shooters will find the Carbon 15 to be their first choice in an AR-15 once they try one.

Carbon 15 Model 97SF, $1,185. Conditional Buy. If you’ve got to have the normal buttstock for whatever reasons, the Carbon 15 Model 97SF can be right for you. You’ll save a hundred bucks over the lighter Model 97F recommended above. However, all of us who tried them both would spend the extra money and go with the lighter of these two super-light rifles, the Model 97F. The 97SF is great, but the lighter one is even greater for just a bit more money.

Bushmaster XM15-E2S Super-Light Carbine, $1,020. Should you buy the Bushmaster? Heck, yes. We gave the Bushmaster a Buy It rating because it was a good rifle, did all it was supposed to, and didn’t break the bank. If you had to scope it, and could live without the carry handle and iron sights, you’d save $90, but (again) we feel these light AR’s are best served with iron sights. If you want a scope and all its weight and precision, why not have a heavy match barrel? See where we’re going? A better arrangement for the Super-Light Bushmaster might be to have a fixed carry handle, so the rear sight would always be with the rifle; and then put a small, light auxiliary handle-mount scope like the fine, unobtrusive, expensive ACOG on it, if a scope were needed. (See June 2001 issue for our report on the $600 ACOG.)

Also from the June issue, comparing the Bushmaster with the American Spirit Arms Corp. Light-Weight Flattop, the Bushmaster was slightly more accurate with two loads. It was a slightly tighter-made rifle, which may have made the accuracy difference. The price of the Bushmaster was slightly higher than that of the Spirit, so it’s a buyer’s choice. Both were good rifles.

Was the Bushmaster’s aluminum alloy receiver more rugged than the carbon-fiber-reinforced version by Professional Ordnance? Aesthetically more pleasing? Depends on the shooter, his experience, and his prejudices. Without doubt, many shooters will reject the Carbon 15 as being a “plastic” rifle, because they want their shootin’ irons to be all metal. But until someone drives trucks over samples of each, or drops ‘em from aircraft onto rocks, we won’t know that answer. We strongly suspect that the Carbon 15 would come out the winner in such extreme tests, based on our collective experiences with carbon-fiber structures in other disciplines besides rifles. It is truly amazing stuff, and those of us who had experience with carbon-fiber products welcomed it to this AR-15 application.

Now that we’ve know what the Carbon 15 is, and how well it works, many of our test shooters have declared that if they had to have an AR-15 rifle, they would absolutely get the Carbon 15. Most said they’d get the lightest version of it with integral iron sights, i.e., the Model 97S. We suspect only the most conservative shooters will go for the slightly more conventional Model 97SF. It adds needless weight, and the takedown of the other, lighter, version is extremely simple anyway.

If you want an AR-15, we believe you ought to assess your intended purchase with a weight scale first. Then look to the other features. We see no reason why any AR-15 intended for field use ought to weigh more than 7 pounds, with 4.5 pounds much more like it.