Sabre Defense M4 Tactical Piston Carbine
By Leroy Thompson
It’s fairly common when I’m at local gun shows or gun shops for shooters who recognize me or already know me to ask me questions about potential purchases. Since I write a lot about black guns, tactical rifles, assault rifles or whatever term one chooses, AR-15 questions are very common. Whenever possible I try to give the best answers I can, but I have to admit that currently there are so many AR-15 variants and so many accessories that I sometimes have to claim ignorance.
That has been the case especially for the last few months as I have been working on a series of books on historical weapons for Osprey Publishing and hence, have done fewer new gun tests than usual. In fact, this article will mark the first new AR-15 I’ve tried in quite awhile.
I think it was the chance to test a new Sabre Defense carbine that made me take a break from writing books. There are lots of excellent AR-15-type rifles on the market designed to fit various budgets. Those from Sabre Defense are generally considered among those at the higher end, both in quality and price. I have a Sabre Defense M4 carbine that I have been using for a few years and rate it among my favorites and, definitely, among the most accurate.
Sabre Defense has a successful background manufacturing parts and weapons for the U.S. Armed Forces, including M16A3 and M16A4 rifles, and Browning M2 .50 machine guns. Sabre Defense is especially known for its high-quality barrels. This experience is apparent in the quality of the civilian and police AR-15-type rifles from Sabre Defense as well.
THE PISTON ADVANTAGE
Previously, Sabre Defense rifles and carbines have used the traditional M4 or M16 Direct Gas Impingement System, in which gas is vented from a port in the barrel and channeled back against the bolt carrier, forcing it backward. This movement causes a cam to rotate the bolt, unlocking the action. However, Sabre Defense has recently introduced two Piston carbines and a rifle. In very simple terms, the Piston system prevents the gases from directly pushing the bolt and, instead, channels the gases against a piston, which pushes an operating rod back against the bolt.
The primary advantages of the piston system are that less debris is thrown back into the receiver, and the rifle or carbine will run cooler with sustained rapid fire. Much of the initial impetus for piston M4s came from within the military special ops community, where operators shoot their guns a lot, really a lot, on full auto doing immediate action drills over and over again until they become automatic. In some cases, reportedly, the guns were getting so hot that there was a chance of the handguards melting, though the heat shields inside the handguards are designed to prevent this from happening.
Both of these advantages of the piston system are most applicable on select-fire weapons. For the semi-auto AR-15, one has to weigh the increased costs of a piston gun versus the advantages. Those who shoot their rifle or carbine a lot may feel the cleaner and cooler running worth the price. I think in many cases, people will choose the piston M4 will because of what those in the special ops community call the CDI (Chicks Dig It) factor. The piston guns don’t just run cooler; they <are> cooler!
I’ve pretty much gotten by with traditional Direct Impingement (DI) carbines, though I do have a Ruger SR-556, which is a piston gun. However, I have been so happy with my DI Sabre Defense M4 carbine that I decided I wanted to try the M4 Tactical Piston Carbine.
I did a bit of research on the Sabre piston system and discovered that it is based on the Adams Arms patented piston system, which many who know more than I do about these matters consider the best system. Sabre Defense engineers did a bit of redesigning of the gas block of the Adams system, reducing its weight and pinning it to the barrel rather than clamping it. To make the piston system even more durable, Sabre Defense treats the gas block, gas plug, piston rod, and bolt carrier with IonBond’s Diamond-Like Coating (DLC). Since the Adams Arms piston comes already coated with a tough Melonite finish, the Sabre Defense piston is well protected.
On the Adams Arms system used by Sabre Defense, the gas plug is easily removable for cleaning from the front of the gas block without tools. The Adams Arms system also isolates the piston rod return spring from heat. Sabre Defense’s piston system vents gas forward rather than under the handguards, another aid to keeping the rifle or carbine clean.
ALL THE RIGHT STUFF
Other than the piston system, the Sabre Defense M4 Tactical Piston Carbine incorporates the other features that make me a fan of Sabre rifles and carbines. The Samson free-floating quad rails allow the attachment of an array of accessories, yet do not affect barrel harmonics and thus, do not affect accuracy. Since the top rail is a “T” rail, optics may be removed and replaced easily in the same position.
I have never been a fan of the standard CAR-15-type sliding buttstock, so I like the upgraded MagPul CTR (Compact/Type Restricted) six-position sliding buttstock on the Sabre M4, which is more comfortable and sturdier. Also a desirable feature is the very ergonomic ERGO pistol grip, which I find especially comfortable when performing operations such as a mag change while the carbine is held against the shoulder in shooting position. An upper extension at the rear of the grip allows it to rest very comfortably in the hand. Within the grip is a battery compartment, a desirable feature for anyone that uses an optical sight or illuminator with its carbine.
Of course, one feature that is always desirable with Sabre Defense carbines is the Chrome-Moly Vanadium alloy barrel. On the M4 Tactical Piston Carbine, the barrel is 16 inches with a 1/7 twist. The 16-inch barrel is fitted with a Micor Flash Suppressor rather than Sabre Defense’s Gill Brake. The Micor incorporates five helical ports that align with the bullet’s gas path to completely vent gases, thus improving accuracy and lowering muzzle flash. For the M4 Tactical Piston Carbine, the piston system is carbine length with detents for easy adjustment or disassembly. A Mil-Spec single-stage trigger offers a very crisp pull, another aid to accuracy.
The M4 Tactical Piston Carbine comes as a nice package with a sling, compact rifle cleaning kit, two magazines, a trigger lock and a soft tactical case. I like the use of the soft case rather than the hard case in which many rifles now ship, as the soft case is easier to stuff into a vehicle or store.
A WORTHY LONG-RANGE SCOPE
Based on the Sabre Defense M4 that I’ve been using for the last few years, I knew the Tactical Piston Carbine would be accurate, so I wanted a scope that would let me do more precise shooting than one of the red dots often used on AR-15s. I chose to go with the IOR Valdada 1.5-8×26 Tactical Illuminated Scope.
I rate the IOR Valdada as one of the best scopes for use on an M4 that will be fired out past 300 yards. On the 1.5X setting, and using the CQB reticle, this is a very fast close-combat scope, yet, when it is dialed up to 8X, its post and stadia lines may be readily used to 800 meters. Combined with Â¼-MOA clicks for zeroing the scope and the illuminated reticle, which includes a setting for night-vision optics, this is one of the most versatile scopes I have ever used.
Since the Sabre Defense M4 Tactical Piston Carbine has a 1/7 twist, it probably would have been better to test it with M855 (SS109) ammunition with 62-grain bullets. However, my supply of SS109 ammo is a bit depleted and due to the high cost of ammo these days, I haven’t replenished it yet. As a result, I did all of my initial shooting with M193 ammo with 55-grain bullets.
A rifle with 1:7 twist is accurate and stabilizes the 55-grain bullet fine even though the faster twist was designed for heavier bullets and especially for tracer ammunition. I still have a fairly good supply of surplus M193, so I loaded up five magazines with 27 rounds each for my initial shooting session. I fired a few rounds at 50 yards to get the IOR Valdada scope close to on, and then put up a target at 100 yards and zeroed it.
IOR’s CQB reticle is designed to be zeroed at 100 yards and can, then, be used for quick shots at longer ranges using stadia lines. Once I had the scope zeroed, I fired groups at 100, 200, and 300 yards, staying a bit more than a minute of angle at each distance, though usually just over. My best three-shot groups at 100 yards were around 1 Â¼ inches, and at 200 yards, 2 Â½ to 3 inches. I also did a lot of shooting at plates between 25 and 50 yards, and found the horseshoe portion of the CQB reticle very fast since I just had to place it around the plate to quickly engage.
The Sabre piston M4 was completely reliable for the 135 rounds I fired on the first session. I did not clean the carbine and fired another 108 rounds—four magazines loaded with 27 rounds—on the second session and once again, reliability was total. One of those magazines was loaded with surplus SS109 ammo, which shot groups around 1 Â½ MOA, most at 200 yards, though I did not break 3 inches on any of the groups.
I concluded that I need to add rail covers, as I was noticing the edges of the rails on my support palm as I was shooting. Many avoid this problem by installing a vertical foregrip, but on semi-auto carbines, I don’t normally use a foregrip unless I install one of the TangoDown models that allow the pressure switch for an illuminator to be slipped in. I may do that on the Sabre Defense M4 Piston Carbine later. For now, I’ve just cut some rail covers to length and affixed them.
Trigger pull on the carbine was crisp and the trigger reset quickly so that I could do fast semi-auto shooting. I have used the same MagPul stock that is on the Sabre Defense carbine on other carbines, and like it. The buttpad is more comfortable on the shoulder, and for me, the position just one in from fully extended is perfect when shooting without body armor.
I did not really do much to take advantage of the piston system, though I did put two magazines through the carbine quickly on plates, but not really enough to test for “cool runnings.” I will try running five or six mags through as fast as I can pull the trigger on one of my next range sessions.
THE VERDICT IS IN
I admit that I like Sabre Defense rifles and carbines, so I expected to like the M4 Tactical Piston Carbine—and I do. It’s going to take a lot of shooting for me to decide whether I will prefer this Sabre over all of my Direct Impingement carbines, including the Sabre Defense M4 I’ve been using for years. I can probably justify the Tactical Piston Carbine with the argument—or for those of you who took Psych 101, the justification—that as I write articles and books about tactical weapons, I should have at least one tactical piston carbine. I’m pretty sure this Sabre Defense is going to be my choice.
Still, when choosing any gun, you have to factor in price. The Tactical Piston Carbine I tested for this article has an MSRP of $2,499. For comparison, Sabre’s standard M4 Tactical with a DI system has an MSRP of $1,993. In either case, what you are paying for is Sabre Defense quality.
Sabre Defense Industries LLC
450 Allied Dr.
Nashville, TN 37211
P.O. Box 270095
Littleton, CO 80127