Suppressors and the SCAR pt 3
In the past I’ve discussed Suppressors and the SCAR. Helping to cut through speculation by discussing how suppressors work and how they work with the SCAR. I further elaborated on the two suppressors known to be specifically designed to work with the SCAR. For background information read here : https://www.handldefense.com/2018/06/suppressors-and-the-scar-part1/ and https://www.handldefense.com/2018/07/suppressors-and-the-scar-part2/
In this installment we are going to discuss the results of our evaluation and testing.
What suppressors need to do is the following: Minimize effects on the weapon, minimize effects on the projectile, eliminate flash, reduce blast pressure, reduce noise profile, while maintaining safety and durability. When looking at these two solutions, this is the criteria that will be used to determine the best option for a SCAR suppressor. All criteria will be scored from zero to one hundred. Some elements are weighted heavier than others.
This testing was done in Arizona. The altitude was 1150 ft ASL, temperatures were between 99-105F, and relative humidity was 28%. The ammunition was used was 7.62×51 150 Grain FMJ-BT Federal American Eagle. We found muzzle velocity at @ 2800 fps. Manufacture states a muzzle energy of 2650 ft-lb which is 3592 joules.
Suppressor effects on the Weapon (20 points)
The OSS Gen V suppressor we are testing was hand built by Russ Oliver for me to shoot 130 grain 7.62×51 from my SCAR. This is the over the barrel two-piece design Gen V with a BPR and SRM. The BPR is the Back Pressure Regulator. The BPR is permanently attached to the SCAR rifle. It threads directly on the barrel. It only adds a small amount of length to the rifle with just the BPR attached. A large portion of the BPR module fits back over the barrel. This can be problematic with some handguards for 13” barrel users. It does provide minimal sound reduction on its own. It is not be exactly hearing safe (155-152 Db). It only added a bit over 2 inches to the length of the weapon. It also added 14.7 ounces in weight.
When the Signature Reduction Module is attached it does provide substantial noise reduction and a much-improved reduction in sound (see below). This also adds a good amount of weight to the weapon. It adds 8 inches in length and 1 pound and 13 ounces in weight. The extra weight and length are very noticeable. With just the BPR attached it’s not as noticed. Once the full system is in place, the center of gravity of the gun is substantially moved forward. The OSS will make the gun very front heavy with lights and lasers attached.
One of the best aspects of the OSS Gen V is that it does not require changing the gas regulator. Russ Oliver tuned it specifically to have no bolt speed increase on the SCAR. I’ve discussed the complications of excessive bolt speed increase on a SCAR previously. This is the strength of the OSS design. Not only no extra energy felt at the shooters shoulder, but our accelerometer confirms, no added G’s on the system. The gas flows through the OSS and is not trapped by baffles, creating no back pressure. The design is hexagonal in shape which is intended to reduce mirage off the suppressor. In application there is a minimal, but noticeable effect until the round count climbs.
The OSS Gen V after a 40 round rapid fire, added 214 degrees F to the barrel. This is somewhat indicative of how much hot gas is being pushed backwards into the gun. How much extra gas might be pushed into the gas system. This of consequence for the SCAR and its gas system (see previous blogs). It also added 412 degree F to the outer skin of the Suppressor. This is indicative of how efficient the suppressor is at evacuating spent gas.
The Surefire SOCOM RC 2 is a quick detach design which is box stock in comparison to my hand built OSS. It fits over the muzzle break provided by Surefire. I like the Surefire muzzle brake on the SCAR by itself. It does require shims to properly index. The break does a good job of reducing felt recoil. The Surefire SOCOM RC 2 is a one-piece design unlike the OSS Gen V. The Quick-Detach mechanism is a simple press and twist, locking collar design. It secures easily and simply.
The SOCOM RC 2 adds 8 inches in length to the weapon. Although its adds 1 pound and 4 ounces to the weapon, it seems lighter and better balanced. This is significant as the OSS is an over the barrel design and the Surefire is an end mount. It does bring the center of gravity of the weapon forward but not nearly as much as the OSS.
When firing the Surefire SOCOM RC 2 you must remember to switch the gas block to the “restricted” or “suppressed” setting at 10 O’clock on the gas regulator. Recoil will be harder and sharper if you do not. The RC 2 is not as soft shooting as the OSS Gen V. Our accelerometer confirms this. We found an average of 6%-8% bolt speed increase with our settings. While this may seem dramatic, I have seen more the 40% bolt speed increase on a SCAR from suppressor use. I’ve seen so much backpressure hinge plates will crack and gas will be expelled from the ejection port. The SOCOM RC 2 is nowhere near that level of added recoil.
The Surefire SOCOM RC 2 added 217 degrees F to the barrel after a 40 round rapid fire session. This is on par with the OSS. This shows not a lot of extra gas is being pushed back down the barrel. The outer skin of the Surefire did gain 457 degree F. This was taken close to the rear of the suppressor, where baffles are known to trap the most heat. Considering the design differences this shows the Surefire to have a very effective baffle system. It only added 45 degrees over the OSS no baffle design, impressive compared to other baffle type designs.
The OSS is a two piece design that requires one half of the system to stay attached, adding bulk and weight. The Surefire allows for complete removal of the suppressor to use a very competent muzzle brake. The OSS also alters the center of gravity of the gun. It always seems to be pulling the gun forward much worse than the Surefire. The SCAR is a light weight gun. Extra weight farther away from the shooter seems to have an amplified effect. The OSS runs marginally cooler than the Surefire, which is actually a good sign for the Surefire’s baffle efficiency. Where the OSS makes its money is the fact that it can be “tuned” to meet a specific weapon, with a specific cartridge, with no effects on the operation of the weapon. If the criteria is to have no effect on the operation of the weapon, the OSS wins. But the Surefire is not that far away in mechanical performance while being superior in handling and features.
OSS Gen V 16 points
Surefire SOCOM RC 2 14 points
Projectile Operation Effects (20 points)
The Weapon was zeroed using no barrel attachments of any type. The trigger was a FN-Herstal OEM trigger. The target was shot at 100 meters using a Leupold Mk.6. The weapon was shot on a supported position under cover. The winds were calm to gusting from the right to left.
I was only going to shoot each suppressor in their complete configurations. I would not shoot the muzzle brake on the Surefire, nor the BPR on the OSS as standalone systems as part of the scoring. The target was placed on an E-type silhouette and three round groups were scored. I was able to achieve a slightly larger than 1 inch group at that distance with the ammo specified in the standard configuration of the rifle.
From base OEM configuration to the complete OSS Gen V suppressor attached, there was a significant change from point of aim to point of impact. The OSS Gen V shot high and right of the target by 3.75 inches. Also, of note when the SRM module is removed the point of aim and point of impact changes slightly again. Once the OSS Gen V is zeroed it does hold regular 1.25-1.5-inch groups. If the Suppressor or one of the modules is removed, there is a noticeable change.
The Surefire SOCOM RC 2 with the muzzle break and suppressor attached, was astoundingly accurate and repeatable. There was effectively little change from point of aim – point of impact from OEM to full Surefire configuration. The shift was ¼ of an inch to the right. Regardless, time after time the Surefire was consistently more accurate.
Throughout testing, it became apparent one suppressor was more accurate than the other. The Surefire SOCOM RC 2 has less effect on the projectile. It was impressive how tight the shot dispersion was throughout the day. Only operator error would cause the rounds to not strike exactly where they are aimed. The OSS does not cause noticeable changes to the projectile when fully configured. It does provide repeatable, consistent accuracy when fully configured. When the SRM module is removed there is a noticeable shift in point of aim – point of impact. When the suppressor is removed completely the changes to point of aim – point of impact becomes glaring.
OSS Gen V 15 points
Surefire SOCOM RC 2 20 points
Flash Elimination (10 points)
Flash Elimination is very important for military applications. A small amount of muzzle flash might be irritating on your next hog hunt under NVG’s in Texas. When returning fire in an ambush in Afghanistan, it is critically important. Often the only thing that would reveal the location of someone shooting is muzzle flash. A pretty big deal when on the wrong side of a PKM.
The first round fired is when flash reduction is key. Suppressors create first round pop and sometimes a flash plume. This can give the position of the user away. While this will go away after the next rounds. It can occur again when the shooter stops firing. What happens is ambient air refills the suppressor chambers. The additional oxygen content is ignited with the first round and causes the flash. The follow-on rounds are moving through waste gas from the fired cartridges, and do not have this problem.
The OSS is designed to eliminate first round pop and muzzle flash. By not using baffles, and instead channeling the gasses and constantly redirecting them, allows for faster venting and cooling. The other advantage is there is no sizable chamber to fill on the OSS. While it might fill with ambient air, it is distributed across the suppressor. While looking at the suppressor during night firing with the naked eye and PVS 14’s, there is no discernible muzzle flash or distinct pop on the OSS.
The Surefire SOCOM RC 2 did have a more of a pop and very irregular first round sparking under NVG’s. The first-round sparks were very small, not a full blown muzzle flash. They appeared after the gun was set on the deck and had time to cool. The Surefire SOCOM RC 2 is probably the best baffle type suppressor I have seen on a SCAR when it comes to muzzle flash. I believe that baffle type suppressors are possibly at a disadvantage.
It would appear that the last baffle, most exposed to the ambient air, seems to refill, cool down, and hold the air needed for the sparks visible under NVG’s. I also have a theory as to why I could see these sparks, dust. I talked this over with a friend who mentions welding grain silos in Ohio. Heat and flames from welding can ignite grain dust easily. Arizona is Middle East dusty, this could be the culprit. Either way, I saw them, I report them.
Simply put the OSS works as designed in this aspect. The patents developed by Russ Oliver to reduce first round pop and flash, are executed brilliantly in this configuration. The Surefire SOCOM RC 2 does a great job in its own right, with minimal pop and some random sparks irregularly noticed. Baffle type suppressors have to work for a broad range of cartridges (Mk 318 130 grain up to 175 grain 118LR). This puts them at a disadvantage against a cartridge matched, designer tuned, OSS suppressor.
OSS GEN V – 10 points
Surefire SOCOM RC 2 – 8 points
Pressure Elimination (10 points)
When firing indoors, firing unsuppressed causes a lot of increased air pressure on the user. When working as a team indoors, another shooter firing right beside you can be distracting. Considering we are talking about shooting a 7.62×51 SCAR 17, it can be significant. Suppressors are used to help reduce pressure. For this test I shot out an open window from a wooden 6×8 storage shed on the range. I shot with the end of the suppressor out of the window, but shot mostly with the suppressor completely inside the room. I also shot from the prone to check how much dust is kicked up when you shoot laying in the dirt.
This part of the test is purely subjective. I had no access to a barometric pressure tester. What was immediately apparent is that with the OSS suppressor seems to cause more over pressure while being shot from completely indoors. The OSS seems to expel more pressure to the front.
The Surefire baffle design seems to absorb more of the energy throughout the length of the suppressor. It seems to give off less energy inside the room. While this is again purely subjective, it seems I would much rather be engaging targets, from an enclosed structure, as a fire team with Surefire equipped SCAR 17’s.
The OSS seemed to kick up more dust when firing from the prone position in the classic dusty and dry conditions found in central Arizona. This is a nuance to most, but could be a tell-tale signature of firing from concealment. Which is a real concern for tactical applications. The Surefire does this as well, but with the OSS it is more pronounced. Yes, one should water down the area in front of your suppressor, with the OSS you need to bring a bit more water. If shooting through a loophole in vegetation it is entirely possible that the forward projected energy could move the vegetation and result in revealing the shooters location.
The OSS just pushes all of its energy out of the front. The Surefire seems to dissipate the energy across the platform before expelling it out the front. This seems to effect use inside a structure. More importantly the signature when shooting from concealed is more pronounced on the OSS.
OSS Gen V – 7 points
Surefire SOCOM RC 2 – 9 points
Sound Reduction (20 points)
Most believe that when it comes to suppressor selection, that noise suppression is everything. While I hope to alter that perspective, it is still the benchmark many use for suppressor effectiveness. I am sure there are other suppressors that are quieter than these on a SCAR 17. This could sacrifice silence over all other aspects and on the SCAR might amplify the adverse effects I have previously mentioned.
There are many ways to judge the Db rating of a suppressor. The two we will use here are industry standard of 5 feet high and 5 feet away form the muzzle. The other is 6 inches from the dominate ear of the shooter preferred by USSOCOM in the Suppressed Upper Receiver Group (SURG) program. Our baseline is the 150 grain 7.62×51 Federal ammunition from a Lantac muzzle brake on a 16” SCAR 17S. We achieved DB ratings from 167 to 170 Db. (5ft x 5ft)
With the OSS Gen V and the DB meter at 5 x 5 ft from the muzzle, results came back at 147 to 142 DB. Of note is that OSHA considers any noise below 140 Db “hearing safe”. When the OSS is tested 6 inches from the shooters dominate ear (SURG) the OSS is quieter than expected. Db ratings came back at 134Db to 129 Db. The OSS design projects its energy and sound to the front. It is comfortable to shoot without hearing protection. Russ Oliver’s design brings the goods in this realm.
The Surefire SOCOM RC 2 was quieter from the front, and louder from the shooters ear. With a result of 140-138 from the 5ft by 5ft distance from the muzzle. The SURG standard at the shooters ear was a max of 138 to 135 Db from the shooters ear. For the shooters perspective you could still shoot it without hearing protection without issue, but it is louder.
I know that many consider quietness the central issue on a suppression. On a SCAR there is more to it than that. Regardless, the OSS is quieter to the shooter. Again a hand built special tuned to the load. The technology, when tuned to the cartridge, by an expert, is damn quiet. The Surefire is not loud, I have heard much louder on this gun for sure. With the OSS pushing its noise and energy downrange, away from the shooter, it wins this part of the competition.
OSS Gen V – 18 points
Surefire SOCOM RC 2 – 16 points
Suppressor Durability (20 points)
One often critically overlooked aspect of a suppressor is its durability. How long can you shoot the suppressor without cleaning or servicing? How long until a suppressor fails from use? Both suppressors are over $1500 in price. You have the tax stamp expense with its associated wait times. Nobody would want to have to spend too much time or money on maintenance and repair. Another aspect is you don’t want the suppressor to fail during operation. While this could just be inconvenient for some, in extreme cases I’ve seen suppressors detonate like a hand grenade. If suppressor can fail under heavy sustained use, that is of critical importance.
Previously I mentioned the USSOCOM Suppressed Upper Receiver Group. In 2015 the Handl Defense Mk.17 Enhancement Program had been submitted as an ECP to USSOCOM. One area that we were going to address was the suppressor. Russ Oliver presented me the solution at SHOT show 2015. A 7.62×51 OSS suppressor designed specifically for the SCAR. I shot the SURG firing table for 5.56 but in 7.62×51. The Russ Oliver built OSS suppressor was able to take more than 4 full SURG Cycles, in 7.62×51.
I knew after SHOT show the future was on the way. I eagerly awaited delivery of the new SCAR specific OSS suppressors. I think it is important to use external experts regularly when discussing items that are subjective and contentious. In relation to the OSS suppressors durability, I will reference two SOCOM experts that we will call Master Sargent O and Sargent First Class T.
MSG O and SFC T were taking an OSS Gen V demonstration model suppressor to a range that is well known in North Carolina. What ended up happening was speculated about ad nauseum in the blogosphere. Here is the reality of the situation. The suppressor that was found to break in dramatic fashion was not made of the high-performance materials required by Russ Oliver’s design. Much like the jet turbine it looks like, the OSS Gen V, if made of the wrong materials, things will fail, sometimes spectacularly. This particular suppressor was not made to Russ Oliver’s specifications, but of cheaper materials.
Unfortunately, I did not know of MSG O and SFC T’s misfortune. Russ Oliver left OSS not long after SHOT show and stopped all communication. The SCAR specific suppressors landed at Handl Defense soon thereafter. We set out to test the suppressors to the standard we had seen at SHOT show. I suffered the same fate as MSG O and SFC T. When we tested the OSS suppressors, they all failed. Then one failed so spectacularly it was like a grenade detonating. I was seen at the emergency room for a concussion and blast injuries.
While the testing was to a standard that represents the worst of combat, it shows that this design unless made of the exact right materials, and tuned by an expert, is only capable of light duty. When it is made of the wrong materials and pushed past its limits, it is potentially dangerous.
In stark contrast is the Surefire SOCOM RC 2. Their durability is legendary. There is a story about a Surefire suppressor that had been shot by another gun and continued to function. There are stories of Surefire suppressors having baffle strikes and still operating. I know there are Surefire suppressors with very high round counts. But again, let us bring in an outside expert on the matter.
I’ve known Bill Blowers for some time. He is a recently retired SWAT officer. He spent 25 years as an officer and 22 of those on SWAT. Prior to that he spent 6 years as a Cav Scout. He and I have attended some of the same tactical schools and worked the same areas. He is the founder of Tap Rack Tactical.
In my conversations with Bill he told me that his SWAT team bought 6 Surefire suppressors back in 2007 (SF 212’s). As of February 2018, 3 of them were still in service with well over 100,000 rounds. That his department never paid a single dime in repairs. This is even though these Surefire suppressors we used constantly, both operationally and in training. The durability was so impressive that his department just bought 150 Surefire suppressors, knowing they would last a decade or more. Also, of note he said that other local departments (his SWAT team was a combined unit of several departments) saw the durability of the Surefire suppressors. That once their Gemtech and OSS suppressors wore out they were replaced with Surefire suppressors. Often these other suppressors would only last about 1 year.
Bill’s findings are consistent with many other organizations and individuals’ findings. Surefire suppressors are known for their durability and longevity. Surefire’s extensive history with the Military and Law Enforcement is fully on display here. Surefire knows what a suppressor must do, they build suppressors that can do it for a long time.
The OSS is potentially hazardous if made of the wrong materials. If made of the right materials, tuned by the right people it could be a revolutionary technology. Unfortunately, when Russ Oliver talked to me about a year after he left OSS, he mentioned the plans and that 4 SURG+ cycle suppressor were both destroyed before he left. I will not recommend heavy use (FA, etc) with the OSS. I understand OSS has a two-tiered offering. Perhaps issues USASFC and I discovered, became a budget material and high-end material solution. Time will tell if it works.
The Surefire SOCOM RC 2 is the utter and exact opposite. It has a history of taking whatever abuse you can throw at it. Durable, robust, built like a tank. While it might not reflect the latest in flow through technology, the Surefire SOCOM RC 2 is leading edge. It takes the proven methodology of baffles and executes it in a way that all the performance requirements are met. Durability is not sacrificed for some other aspect. Most shooters could buy a SOCOM RC 2 and never out shoot its service life.
This part of the competition was as starkly different as it possibly could be. One suppressor was confidence inspiring, seamlessly taking all the work you can give it. This OSS held up fine. But, this example is hand built by the designer to the specifications developed for Handl Defense’s SCAR program. Also, there are examples of spectacular failures. Even though light duty should be fine, how do you know what you are really going to get when you need to get busy?
OSS Gen V – 8 points
Surefire SOCOM RC 2 – 20 points
The intent of the evaluation is to provide the reader with the best possible immediate solution for a suppressor solution for the SCAR 17. We have identified the potential issues of how suppressors not designed for the SCAR can cause havoc. We then identified the two suppressors verified to have been designed with SCAR experts directly involved with the design and development, that are currently available for purchase.
We then set out the criteria for what the suppressors need to do. We determined Suppressors need to: Minimize effects on the weapon operation, minimize effects on the projectile, eliminate flash, reduce blast pressure, reduce noise profile, while maintaining safety and durability.
The OSS Gen V was better at causing less adverse effects on the rifle, no infrequent sparks being launched from the muzzle, and reduced noise profile. The Surefire SOCOM RC 2 was not far off in causing adverse effects on the rifle and was little bit louder.
The Surefire SOCOM RC 2 allowed for more accuracy, easier handling, better reduction in blast pressure, and is much more durable. The OSS Gen V was still accurate when fully configured but accuracy suffers when configurations are altered. The OSS has a good deal more blast pressure to the front. The OSS really suffers under heavy use, to the point of being questionably safe.
The OSS Gen V is much more suited to a bolt action sniper system or Semi Auto Sniper System that it was designed for. The OSS Gen V is for those wanting to build a SCAR 17 into a Mk.20 type clone, where the round count and rate of fire will be low. Where the extra weight and change of balance will not be as important being shot from a bi-pod. For those who will build a SCAR that will not need much change in its configuration or light use, the OSS Gen V would be suitable.
For everyone else the choice is clear, the Surefire SOCOM RC 2. I took part in the development of the OSS, and this one is hand built by the designer. I thought this might be an unfair fight for the Surefire, but after testing it is clearly apparent. The Surefire is much better suited for the SCAR 17s intended role, a battle rifle. A light weight, flexible, and accurate weapon that can do whatever the user asks. The RC 2 has very little adverse effects on the gun, keeps the weapons accuracy on or off the gun, hearing safe, and has less overpressure issues while shooting indoors. But more than any of this the Surefire SOCOM RC 2 will last as long as the rifle does. When the expense and hassle of purchasing and repairing suppressors are considered, the choice is clearly apparent. The best choice for a SCAR 17 is the Surefire SOCOM RC 2.
OSS Gen V – 74 points
Surefire SOCOM RC 2 – 87 points