It is no surprise for us to state that sniping has evolved over the years and it is also nothing revelatory to indicate that semi-auto rifles are a part of that evolution. There have been semi-automatic sniper rifles since World War 2 and they have found a place among snipers even in today’s army. The US Army incorporates the M110 and now the M110A1 as a standard issue sniper rifle, both of them being based on AR10 style platforms and chambered in .308 Winchester. We have reviewed several semi-auto rifles over the years, but with the ever changing role of the sniper and the need for higher firepower, we have begun to look even more deeply into the role of Semi-automatic Sniper Systems (SASS) and the role of the designated marksman. As a part of this deeper dive into these topics, we have ourselves been looking at the available SASS precision rifle manufacturers and have heard very good things about Aero Precision and have been impressed with the quality of parts that come out of their factory. So we thought we would take a thorough in-depth look at one of their complete SASS rifles, the M5E1, chambered in 6.5 Creedmoor. Aero will build their rifles to customer specs, and our specs included a 20″ barrel, M5E1 platform, with the precision buttstock and Geiselle trigger.
Aero Precision has it roots in the Aerospace manufacturing industry, which their name makes pretty obvious. Their introduction into the rifle building market began by initially making OEM parts for other AR manufacturers, and that is still a major part of their business. But in about 2012 they started a customer facing business as well and their reputation has been outstanding for their exceptional quality control and tight tolerances. These are traits that were brought over them their Aerospace experience where companies like Boeing were their customers. In the Aerospace and Defense sectors, tight tolerances and quality control are not just desirable, but mandatory.
The M5E1 comes in a durable cardboard box with egg-crate style foam on the inside and with all of the normal paperwork that one would expect. There are base versions of the rifle that are available pre-built with various colors and barrel lengths. But Aero also allows a buyer to change up some of the items as well, such as the muzzlebrake and trigger. The rifle arrives with a build sheet listing the ordered specs and there is some additional documentation and owners manuals included as well. The initial inspection of the rifle shows uniform and even metal finish work and quality cut parts with a high level of finish to all edges and assembled parts.
As has become common on precision AR/MSR based rifles, this version of the M5E1 utilizes the latest generation of the Magpul PRS fully adjustable buttstock. This stock has adjustment knobs, with pronounced clicks, for both the length of pull as well as an elevated cheek rest. As is the Magpul norm, the stock is made from polymer which has become their specialty. There is a soft recoil pad on that adjustable buttplate that helps absorb the recoil.
Just in front of that recoil pad is the vertical oriented adjustment knob for the length of pull. The knobs do not have any locking mechanism, but they have stiff clicks that both hold the adjustments in place as well as make it a bit difficult to rotate. The adjustable cheekpiece uses the same style of adjustment knob, but it is oriented horizontally below the cheekpiece. The clicks are just as stiff as the length of pull knob and they too hold the cheekpiece in place. The cheekpiece itself is made of the same polymer and adjusts to a nearly flat position when all the way down. That polymer can get a bit slippery when sweat and face-paint are thrown in the mix. There is also a flush cup receptacle on the side of the stock toward the front, just below the buffer tube.
The upper receiver is the Aero Precision M5E1 which includes the standard forward assist and brass deflector on the right hand side and the fire selector switch on the left hand side. We like the symbols used for fire and safe on the both sides of the receiver. The rifle can be fired left handed, but it is indeed setup for right hand use in typical AR manner. The upper receiver is robust and has some flat surfaces making up a hexagon style design. The upper is also a flattop design with an integrated rail with laser etched T Markings along the slots. The upper is made from 7075-T6 forged aluminum and shows high quality of manufacturing and finish. M4 feed ramps are also a standard part of the Aero M5 uppers.
One of the features of the E1 enhanced uppers is that the barrel nut and handguard mounting are an integral part of the upper receiver which not only makes assembly easier, but makes for a solid single piece unit. The downside is that the handguards have to be compatible with their proprietary system and currently only the Aero handguards are.
The standard pistol grip on the M5E1 rifles is also a Magpul product, the MOE grip in this case. It is a hard polymer plastic again with some nice texturing on it to provide a good gripping surface. The AR grip location and shape has always done a good job of placing the firing hand in the proper location to get a good trigger pull. The trigger that is being pulled on our test rifle is the very popular Geiselle SSA-E two stage trigger. These triggers have a very good reputation as being some of the best AR triggers on the market, helped by their use on the Mk12 series of SPR rifles as well as others. The trigger is very smooth for an AR trigger with the first stage taking just a bit over 2 pounds to pull and then the second stage breaking clean at 4.1 lbs according to our digital trigger scale.
The trigger guard is machined as part of the lower receiver and is enlarged to allow the use of gloved fingers without a problem. The magazine release is located in the normal AR position and is easily reached by the trigger finger. The mag release ejects the magazine clean without issue. The rifle comes with a Magpul PMag 7.62 magazine of 20 rounds and any of the normal 308/7.62 LR/SR PMags work great in the rifle.
The controls are all basic AR/MSR, including the bolt release and charging handle. The charging handle on our rifle was their standard handle with the release only on the left hand side, again, configured for a right handed shooter. The size of it is large enough to allow for operation with a scope mounted, though its a bit tight. There is an optional charging handle that is ambidextrous with a larger T as well and that one would work a bit better with a scope mounted.
The bolt carrier group is completely machined by Aero Precision to very high standards and includes case hardening and proper Grade 8 parts. The Aero logo is laser engraved on the right hand side and the BCG is available in three different finishes. Phosphate, Black Nitride, and Nickel Boron if you wish for a silver finish. Our rifle has the Black Nitride finish. Additionally, all of the bolts feature a steel extractor with double O-rings and double springs for durability and reliability.
The handguard is a 15″ version of the Aero Precision handguard with M-Lok slots machined into it. As was mentioned, this is one of their own designs that mates up to the M5E1 upper receiver with only eight screws and is a full freefloating handguard. There is also a rail along the top that properly mates up to the rail on the upper receiver to provide a monolith rail down the entire length of the upper receiver and handguard. There are also flush cup receptacles on both sides of the handguard as well as one on the bottom. This style of M-Lok handguard is very metalic feeling, though with lots of available M-Lok slots for flexibility of mounting accessories. If you do not like that metallic feeling, there are many different options for M-Lok rail covers from many different manufacturers. Honestly, we will likely be getting some for this rifle.
The barrel on our rifle is a 20″ heavy barrel chambered in 6.5 Creedmoor with a 1:8″ rate of twist. The rifles are available in either 308 Winchester or 6.5 Creedmoor, both are good options. The barrel is 416R stainless steel with a bead blasted finish to it. For tactical use, some spray paint of Cerakote would be desired to aid concealment. The factory finish is more of a matte grey and could be usable if needed. We measured the diameter of the barrel at the muzzlebrake at .859″, though Aero indicates the barrel takes a .875″ gas block journal. The taper under the handguard is a straight taper down to that gas block.
The muzzlebrake is an Epsilon brake with multiple chambers and a flash hider style end. It is finished in Anodized black which matches the rest of the rifle, but is a contrast to the matte silver barrel. We specified a 20″ barrel length as it is a good length and a solid compromise for this style of DMR allowing the 6.5 CM cartridge to get some extra velocity over shorter barrels. Yet it is not too long to make the rifle unwieldy in the field. The muzzlebrake does add several inches to the overall length and if you wanted a more compact setup, an 18″ barrel is another good option to consider.
The overall fit and finish of the rifle are nice throughout with the anodizing having an even finish and appearance over the entire rifle. The M5E1 feels solid in your hands and when we put it on the scale it came in at 11.2 lbs (5.09 kg) without any optics which is fairly hefty for a DMR. Though it is perhaps a tad lighter than the average modern sniper rifle. A lot of that weight is in the barrel but the rifle is well balanced and not nose heavy.
We liked what we were seeing with the overall package after our inspection, but of course, we needed to see how it would perform. For our shooting tests we decided to utilize a Sightron S-Tac 3-16x42mm scope which would make a good combination for the capability and role of this rifle. For AR/MSRs, the scopes normally have to set up higher than a normal bolt action due to the buttstock placement, but with this M5E1 and its PRS stock, that was not an issue. We used a set of Nightforce high 30mm rings which gave us just a tad of clearance above the top rail and with the adjustable cheekpiece at its lowest setting we had perfect eye alignment with the scope nice and low, as desired.
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The flexibility of the M-Lok handguard came in handy as we mounted a Magpul aluminum M-Lok swivel stud up front in order to mount a Harris bi-pod. Mounting it was quick, simple, and the handguard gave us all the flexibility we wanted.
When deciding on which ammo to use for our testing, we tried to get a wide assortment of bullet types and weights. For the 6.5 Creedmoor we have not yet come up with a standard factory match load that we know will perform well in all rifles. For the .308 Winchester rifles that we test we always use Federal Gold Medal Match 168gr as one of our test loads. This load is the go to load for most LE sniper teams and usually always performs well. For the 6.5 CM, we haven’t found that load for sure yet, but the Hornadly 140gr ELD is our current front runner and so we brought that load. The other three loads we tested were the Sig 140gr OTM Elite Match, Federal Gold Medal Berger 130gr and the Choice Ammunition 123gr Scenar.
With our ammo now in hand and all of our equipment with us, we headed out to the range on a nice summer Montana morning. The skies were sunny, the temperature was a refreshing 51 degrees Fahrenheit but there was an unusual brisk breeze blowing about 5-8 mph. If you are not familiar with how we test rifles, please read the article How We Test Rifles and Scopes. We insured that the rifle was lubed and then settled down for our 100 yard accuracy tests. The results were as follows:
|Ammunition||Average Group||Best Group|
|Choice 123gr Scenar||1.235″ (1.180 MOA)||.744″ (.711 MOA)|
|Federal 130gr Gold Medal Berger||1.119″ (1.069 MOA)||.420″ (.401 MOA)|
|Hornady 140gr ELD Match||1.274″ (1.217 MOA)||.850″ (.812 MOA)|
|Sig 140gr OTM Elite Match||.687″ (.656 MOA)||.572″ (.546 MOA)|
For a semi-auto DMR we do not require the same accuracy demands as we do for a sniper rifle that we intend to carry in the field. Typically the minimum accuracy standard we like for a sniper rifle is sub 1 MOA, though we would prefer our averages to be as tight as possible and would like to see sub .75 MOA. For a DMR where increased firepower with extended range are desired over ultimate accuracy, we say 1.5 MOA will do with sub 1.0 MOA being desirable. That would still give the Designated Marksman 800-1000 yard capability without demanding a sacrifice in reliability or firepower. It would also allow the flexibility of the rifle being used in the sniper role if needed.
With the above standards in mind, the Sig 140gr OTM Elite Match ammunition obviously exceeded those standards and averaged .656 MOA and was easily the most consistent of the ammo tested. The Hornady did not perform as well as we have seen in other rifles, but all of the ammo tested exceeded our 1.5 MOA minimum for DMR work. We of course would have loved to see a .5 MOA rifle, but we were more than happy with the performance. We had to keep in mind that these are factory produced semi-auto rifles and not custom built bolt guns. Additionally this is a brand new rifle that is just getting broke in and there is some additional accuracy potential.
The recoil on the rifle was extremely light and follow up shots were easy and very quick. With a good portion of the the shots we did not lose the target picture when firing and were able to remain on target through the recoil. This is a critical trait for a DMR as it allows that heavy firepower to be effectively and rapidly brought on target.
As you would expect based off of our accuracy tests, we selected the Sig 140gr OTM ammo for our 300 yard head shot test. Due to the semi-auto capability and low recoil with excellent control that this rifle exhibited, we expected a quick time during this test. We were not disappointed. Firing the three rounds took only 7 seconds. One of the hardest things to do as a shooter is to control yourself and take your time when the stress is on. That stress tends to cause the shooter to rush their shots and the groups will tend to open up. Adding the time aspect of this test is intended to replicate this stress to some degree and this was probably the biggest challenge when firing the M5E1 in this test. The group came in at 5.450″ (1.735 MOA) which was larger than we would have liked, though it was nicely centered right on the head.
|300y Head Target Test|
|Time Score (7 secs)||137.1|
|Accuracy Score (1.735 moa)||34.6|
The high total score of 171.7 was primarily due to that very quick firing time, the fastest we have accomplished to date. That score puts the M5E1 in the current top 5 even with accuracy that we think can be improved on.
Of course, all of the normal squawks that pertain to semi-auto rifles pertain to the M5E1 as well. Reliability will never be as good as a bolt action. Maintenance in the field is more advanced and difficult, yet even more critical for prolonged operational use. They are a pain to clean, which is also important for reliability and maintenance, and they fling brass all over the place. With a DMR, leaving target identifiers, such as ejected brass, is not as paramount as it is when operating as a sniper, and brass catchers do exist, though they are bulky and get in the way when doing sniper things. We were curious as to just how far the brass gets ejected on the M5E1 so we fired from the prone position on level dirt, not concrete, and measured the distance the brass was ejected. The distance was right at 7 feet away and to the side and back, the normal direction for AR/MSRs with brass deflectors. Not that that information was crucial, but we found it interesting.
Speaking of the issues that can pertain to semi-auto rifles, we would be remiss if we did not mention the reliability of the M5E1. In all of our firing, we did not have a single jam, misfire, failure to feed or any other issue. It did not matter what ammo we used, though in all honesty it was all high quality match ammo. We primarily used a ten-round PMag, but we loaded it full, partial, single round, etc and there was never a problem. The rifle ejected all the spent brass without issue and the rifle just functioned. We never even lubed the rifle again after the initial lube before we started testing.
The Aero Precision M5E1 is a very capable long range DMR that has excellent build quality for a production based rifle. We were impressed with its features, reliability and the accuracy was good. For a DMR, these rifles, in either .308 Win or 6.5 CM would fit the requirements very well. We would be very interested in testing a .308 version side by side just to see how it does as the .308 Ammo selection is much more mature with known capabilities than is the newer 6.5 Creedmoor. Obviously, the 6.5 CM has a significant advantage at long range work though.
We had an Aero Precision rifle come through one of our Long Range Precision Marksman classes this year and it did very well out past 1000 yards. If you are looking for a semi-auto built on the large AR10 (MSR) platform, then the Aero is certainly worth looking at. We certainly will be for some of our future projects!
Sniper Central 2019