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Shorty USA Reviews the PolarStar PR-15 EPAR

Unless you have been living under a rock for the last few years you have undoubtedly heard of a U.S.A. based company called PolarStar. Located in Delaware, PolarStar Airsoft, a division of PolarStar Engineering & Machine, has been making a name for themselves in the airsoft world by manufacturing high end aftermarket upgrade parts for such sniper rifles as the Tokyo Marui VSR-10, Maruzen Type 96 and the Tanaka M700. What you may not know is that for the past several months PolarStar has been working on something that might just change the sport of airsoft forever.

You may have caught a glimpse of the semi-secretive project in a short YouTube™ clip or a blurb on the odd forum or two, although there really hasn’t been that much information to be found. Many have speculated that this “Loch Ness Monster” would never emerge and have written it off as just another extravagant experiment. Well, ladies and gentlemen, those doubtful individuals had better prepare to eat their boonie hats with a side of crow because today Shorty USA is proud to be the first to review the production sample of the PolarStar PR-15 EPAR. That’s right, production. This is not an experiment, concept or prototype. This one is going all the way.

The PolarStar PR-15 EPAR looks no different than any other ordinary M4 series AEG on the market today unless you notice the short section of macroline protruding from the rifles pistol grip. In fact, externally the rifle is literally a full metal VFC body with PolarStar trademarks. It is what lurks at the other end of that macroline which makes this rifle truly extraordinary. That is because EPAR stands for Electro-Pneumatic Airsoft Rifle. It runs off of HPA and it is going to kick the gear grease out of your AEG.

(Click to view Shorty USA's YouTube™ teaser demoing of the PR-15 EPAR rifles along with a PolarStar DMR and SAW equipped with the PolarStar HPA Fusion Engine)

HPA airsoft guns aren’t new. What’s so great about this one?

While HPA (High Pressure Air) powered airsoft guns have been around for decades, there hasn’t been one like the PR-15. Those “Classic” guns such as produced by Escort and Daytona used traditional mechanical sears and valves to function. While this level of technology worked for Noah’s Ark, PolarStar decided it was about time we stepped up to the computer age. The PR-15 uses PolarStar’s patent pending Fusion Engine which is a solenoid driven, electronically controlled, HPA drop-in replacement for an AEG’s gearbox.

What is the benefit of the Fusion Engine over the old Classic?

The Classic guns of the past were limited as far as scenario adaptability due to their cyclic rate and muzzle velocity being directly linked to how much pressure was being fed into the gun. You could not increase one without increasing the other. Therefore, if you were tasked with a close quarters mission, you could not adjust your rifle to have a high rate of fire and still be within safe velocity limits at the same time.

The beauty of PolarStar’s electronically controlled system is that you can adjust the rifles muzzle velocity and cyclic rate individually. Their engine is fitted with two independently operated solenoids allowing for complete control of its components via an FCU (Fire Control Unit) which is located next to the rifles battery similar to how a MOSFET would be wired into an AEG. The FCU enables you to tailor the rifles mode of operation to best fit your application or scenario by using its on board LCD display and five position joystick style tactile switch.

For example, say you wanted to make your rifle fire in burst mode instead of full auto. Not only is that possible via the FCU, but you can even adjust how many rounds are fired within that burst. The system is also smart enough that it will stop the rifle from firing if the trigger is released part of the way through the burst just like a real rifle would. You can also set the rifle to be semi auto only for DMR configurations.

If you decide the rate of fire isn’t quite where you want it, you can use the FCU to adjust how fast the rifle cycles. With the Fusion Engine you will actually have the ability to set up your rifle to mimic the exact same fire modes and cyclic rate as its real steel counterpart.

The capabilities of the FCU don’t stop there either. You’ll also have the option to fine tune the system for the best possible performance. For example, you can adjust how long the air nozzle will stay back to ensure proper feeding when you are configuring the rifle for a high rate of fire. You can also change how many milliseconds after the air nozzle is released before the rifle will fire. This is so when you're using heavier rounds, such as a .4g in a DMR configuration, you can adjust for the extra time needed for the round to be chambered in order to get the perfect air seal. You can also adjust the volume of air which is released to take full advantage of longer aftermarket barrels.

You’ll even have the option to select whether you want the rifle to cycle the air nozzle and chamber a new round first before firing, or fire first and then chamber a new round in a true closed bolt configuration.

This all might sound very complicated but with the easy to use menus on the FCU’s LED screen, it is actually easier than changing settings on your cell phone. And if you do happen to get the system all discombobulated, PolarStar has built in a factory default which you can easily reset the system to in the event you just want to start over.

Is the Fusion Engine built on an AEG’s gearbox?

While it may look very similar, the only connection the Fusion Engine has to an AEG’s gearbox is that it can replace it. This system is not some hair-brained contraption slapped together with bubblegum and duct tape in someone’s basement before being retrofitted into an actual AEG gearbox. The Fusion Engine was built from the ground up using state-of-the-art computer modeling, CNC machining and the same level of quality and engineering seen in PolarStar’s upgrade parts. It is also 100% “Made in the U.S.A.”.

You see, even though PolarStar didn’t break into the airsoft industry until a few years back, they are not just a bunch of guys that one day decided “Hey, let’s buy machining equipment and make some nifty parts!”. PolarStar Engineering & Machine has been in the engineering business for well over a decade and specializes in servicing the automotive racing industry by designing and crafting high end performance parts. They also design, engineer and produce ballistic testing equipment for both the government and private sectors.

Needless to say, when it came to engineering the Fusion Engine they didn’t go by guess and by God until something started working. Every aspect of this system has been refined after hours of meticulous testing to ensure it performed to their standards. These guys even used high speed cameras to record exactly how the system behaved to aid in its development.

What kind of performance can I expect?

The Fusion Engine was not built just to be some high-tech novelty with a bunch of flashy features and shiny parts. Its lead designers, Ben Noji and Jordan Anderson are avid airsoft enthusiasts who, working alongside Manufacturing Engineer Steve Hague and Journeyman Toolmaker Ray Biliski, have together built this little monster to be a serious contender in the world of competitive airsoft.

(These readings were taken during the “torture test” to find the RPS and FPS limits of the Fusion Engine. The production model will have a safety blow off to limit the system to a safe performance level. Production models will NOT be able to reproduce these numbers. Readings are with a .2g BB)

In regards to muzzle velocity, the Fusion Engine allows the velocity of the PR-15 rifles to be adjustable from CQB friendly to the outer limits allowed to field rifles. By changing the pressure on the air tanks regulator, an out-of-the-box PR-15 Carbine can produce muzzle velocities ranging from approximately 330 fps all the way up to 450 fps using a .2g BB. This makes it possible for these rifles to be used in a CQB arena for one game and then calibrated to be used as field rifles for the next with only a few minutes of downtime in-between.

If you already had plans of a high powered DMR rifle dancing through your head and were hoping for a slightly higher muzzle velocity, you will be pleased to know that PolarStar is already working on aftermarket air nozzles specifically designed for DMR applications. Their prototype “High Flow” DMR nozzle enabled our test rifle to reach velocities of 475+ fps using a .4g BB and only a 509mm barrel. The high flow design of this nozzle will let an increased air volume in behind the BB while still providing ample back pressure to keep the rifle at an exceptionally fast cyclic rate when operating in the higher pressure ranges. Also, since these rifles can produce more air volume than physically possible with an AEG, someone who wanted to build a DMR can capitalize on a longer aftermarket barrel which would otherwise be pointless in an AEG. This is because the air volume which AEG’s can produce is limited to the capacity of their cylinders. At a certain point adding more barrel length to an AEG will actually have a negative affect on the rifles performance since it can not generate the air volume needed to accelerate the BB down the entire length of the barrel. That doesn’t happen with the Fusion Engine since you have an unlimited supply of air which is adjustable via the FCU. Also, due to this higher volume of air, you will not get the drop off in muzzle energy when you use a heavier weight BB as you would with an AEG. In fact, when using heavier rounds such as the .4g you will actually see an increase in muzzle energy with the Fusion Engine.

Then for you players out there who like to mix it up in CQB, you’ll be interested in their restricted “1 Joule” nozzle which will limit the rifle to no more than 328 fps with a .2g BB regardless of how much pressure you pump through the system. Since this nozzle will produce a much higher back pressure it will enable your rifle to achieve insane fire rates and increased air efficiency.

The High Flow, Standard and 1 Joule nozzles will all be color coded in Mil-Spec anodizing for easy identification.

The PR-15 rifles are equipped with a one piece hop-up and barrel just like those found in a traditional VFC AEG. From their background in making sniper rifle parts, PolarStar knows that the less a barrel moves the more consistent the rifle will shoot. So, they actually designed the front of their Fusion Engine so that it would interlock perfectly with the hop-up system making it so their barrel group stays rock solid. Also, since their system always produces the same exact amount of air volume, these rifles can achieve a higher level of consistency downrange than your average AEG.

Since the end users preference regarding barrel tolerance and material can be very diverse, PolarStar opted not to fit their rifles with upgraded barrels so customers would not have to pay for a barrel they don’t want. Since the PR-15 does use the same barrel components of an AEG, the end user will have the option of using their preferred AEG barrel.

Cyclic Rate:
The PR-15’s rate of fire can be adjusted anywhere between 500 rounds per minute (8.3 rps) to 1,800 rounds per minute (30 rps), regardless of the muzzle velocity. These statistics are highly conservative since the cyclic rate is really only limited to the magazines ability to keep up with the rifle. We found you can attain the highest rates of fire with standard or mid capacity magazines since most high capacity magazines simply didn’t have the spring tension needed to keep the rifle supplied with BB’s at the higher rates the system is capable of achieving. With minimal tweaking we were able to hit 2,200 rounds per minute (36 rps) and still have the rifle feeding reliably at 450 fps w/ .2g. And that is with the standard nozzle!

Can it use AEG magazines?

Yes, the PR-15 is compatible with most any M4/M16 AEG magazine because externally the rifle is identical to an AEG. So, not only is it compatible with AEG magazines but it can also accept external modifications just like a regular AEG can.

How are the externals?

PolarStar has chosen to use VFC ES series externals for their PR-15 series. If you are not familiar with VFC, when it comes to quality bodies they are one of the best out there. Their receivers are constructed using lightweight aluminum with extremely wear resistant Mil-Spec anodizing. Their furniture is molded from high grade polymer which looks and feels just like the real deal.

These rifles feature a working bolt catch so the bolt stays back after releasing the charging handle so you do not have to juggle the rifle while holding the charging handle back with one hand just so you can adjust the hop-up with the other. Just cycle the charging handle, adjust the hop-up and when you are done slap the release and the bolt snaps forwards like the real thing.

PolarStar informed us that the anodizing on the demo models has a slightly different finish than the production models which will have a matte black finish. The production models will also have milled trademarks which will be deeply engraved into the metal instead of the laser etched markings on the demo. Each rifle will also feature its own sequential serial number on its receiver in place of the demo number.

It sounds cool, but really what advantage does it have over an upgraded AEG?

The main advantage the PR-15 has over an AEG has more to do with its vastly superior mechanics rather than its ability to shoot faster or farther.

Reliability and Maintenance Cost:
The AEG, while being a very capable design, does have a few drawbacks when it comes to longevity. For one, its gearbox is filled with a vast amount of small parts all of which move at insanely high speeds. These parts are prone to wear down and break especially when pushed to the limits demanded by high velocity field and high cycle CQB configurations. Rebuilding, repairing or modifying these gearbox’s is a very time consuming, complicated and expensive operation.

As previously mentioned, the Fusion Engine can be configured to do in minutes what could take several hours and a few hundred dollars to do with an AEG. With Polarstar's system you will never have to deal with the frustrations of shimming gears or installing uncooperative springs again! You only need to adjust some settings on the FCU, turn a valve and your rifle is “upgraded”.

The main function of the Fusion engine is carried by just two parts which are the air nozzle and the poppet valve. These are controlled independently by their own solenoid and as far as moving parts go, that’s about it. You could always say the selector plate is a moving part, but like everything else it is CNC machined from a solid piece of aluminum so that’s going to be around for a while. There’s the trigger switch, but since it is rated for 100,000 cycles (that’s trigger pulls, not total shots fired) chances are you would get carpal tunnel before you wore it out. Even if you were able to wear out the trigger, the replacement switch board would cost under $10. Really, the only parts which could conceivably wear out over time are a series of o-rings and those could be replaced for about the cost of a pack of gum.

Operating Climates:
Aside from the obvious mechanical advantages the Fusion Engine has over a gearbox, the PR-15 rifles also have an advantage when it comes to operating climates. When the mercury drops below freezing the risk of breaking a tappet plate or cracking a gearbox shell increases dramatically since these components are made from plastic and cast metal. With the Fusion Engine, arctic operations are a go because this system is constructed from aircraft grade aluminum both inside and out making it very resilient to sub-freezing temperatures.

Also, AEG’s require a lot of amperage to operate and since batteries do not produce amperage very well when they are frozen you often see decreased performance and find yourself running out of juice a lot faster than normal. Since the Fusion Engine is a low amperage system it can operate just as well in sub-freezing temperatures as it can under normal temperatures.

In case you are concerned that the electronically controlled system might have trouble if it happens to start raining, you don’t have to worry about this anymore than you would with an AEG. The internal electrical components of the Fusion Engine are covered in a protective coating so the PR-15 is no less water resistant than an AEG.

Response Time:
Probably one of my favorite aspects of the Fusion Engine is how responsive the system is and how it sounds. Before an AEG can fire it requires a motor to spin several revolutions, three gears to turn, a spring to compress and a piston to slam forward. This does cause a slight time delay and can sound more like a symphony of out of tune sewing machines rather than a gun. When you squeeze the trigger on a PR-15, the rifle fires instantaneously. There is no motor noise, no whining of gears and no clunk of a piston going forward. When you squeeze off a round with this rifle, the only thing you hear is a very intimidating crack from the muzzle. Also, since the only sound the rifle produces comes from the muzzle you can drastically change the rifles report by adding an amplifier or other aftermarket “attachments”.

(audio clip of the Reaction to Contact drill recorded from a distance)

What kind of battery does it require?
While the PR-15 does need electricity to fire its solenoids it requires very, very little power to function. The PR-15 will come set up with Tamiya connectors so it can use conventional airsoft batteries which you might already have. The system can handle batteries ranging from 6v to 12v although adding extra voltage has zero affect on how the system operates. In fact, since the Fusion Engine draws about 0.01mah per shot, it is even possible for the whole system to operate on a traditional Duracell 9V battery for well over 40,000 shots. So, if you are using regular AEG batteries which have a much higher capacity, you would probably be measuring the time in-between charges in months rather than days.

Does it require an external power source?
Yes, the PR-15 does require an external air rig which comprises of a remote line, stabilizer and HPA tank. These rigs and tanks are made for paintball guns by such companies as Palmer Pursuit, Guerrilla Air and Ninja Paintball. PolarStar also says they will be offering pre-assembled air rigs for their rifles in the near future.

The external air rig is probably the one and only aspect of the PR-15 that some of you will find discouraging because you don’t want to run around looking like Scuba Steve or one of the Ghostbusters. This I think I can help you with because I completely hated the idea of having my rifle tethered to an external tank. However, I, along with two other Shorty USA staff members, were invited to attend the 2010 Operation: Irene with PolarStar where we fielded five prototypes of their 1st Generation HPA system in their first ever field test. Talk about baptism under fire!

After the initial 15 minutes of the first game one of the PolarStar guys asked me how I was liking the air tank in my pack and I suddenly realized I had forgotten all about it. During the next day and a half of fighting the air rig never once inhibited my ability to transition between strong and weak side, slinging the rifle on my back or quickly detaching it from my gear. It didn’t slow me down as I scaled ladders, negotiated small rooms, cleared stairwells and ran through thick woods. It didn’t even stop me from doing a well executed but poorly planned combat roll. After that weekend I was completely thrilled with the set up and started considering which of my many AEG’s I should sell first.

The air tank fits inconspicuously into a hydration pack or you can even put it in a canteen pouch on your belt. When you have your rifle on a sling you really can’t distinguish what is the sling and what is the rig so you soon forget you even have it on. As far as needing to detach yourself from your rifle, the air line can be fitted with a quick detach coupling that can be disconnected faster than the time it takes to change a magazine.

How will these rifles be regulated for events with FPS limits?

A lot of people have been bringing up this concern due to the systems ability to easily adjust muzzle velocity. What most people forget is that paintball guns use this same type of air rig and officials have been successfully regulating muzzle velocities at national tournaments for decades. There are devices called tournament locks, which after the rifle is adjusted and chronographed to regulation velocity, are locked over the regulator and sealed so that one could not tamper with their velocity afterwards.

Also, as previously covered, the rifles air nozzles will be color coded to help officials recognize the performance capabilities of each rifle. And, while changing out an air nozzle on one of these systems isn’t exactly hard, it can’t be accomplished on the fly during a game.

Besides, there are several AEG’s out there which now feature quick change springs or adjustable spring guides to quickly change the rifles muzzle velocity. So really, a PR-15 with a mandatory tournament lock and its color coded air nozzle would be easier to regulate than a lot of these newer AEG’s.

How many shots can you get out of an air tank?

It isn’t really possible to give exact numbers since it can vary depending on the maximum pressure and capacity of your tank combined with the pressure you are running the system at. However, to give you an estimate we have come up with an equation to calculate the endurance of the air tank. These results were from a PR-15 CQBR running at 400 fps w/ .2g BB. Since the rifles efficiency will only increase with the length of the barrel these results are highly conservative.

Efficiency Equation:
Air Tank Pressure (tanks maximum psi) / 100 X Tanks Size (cubic inches) = Total Shots Available

3000 psi 48cu tank, running @ 110psi (avg. 400 fps w/ .2g) = approximately 1,440 shots

4500psi 50cu tank, running @ 110psi (avg. 400 fps w/ .2g) = approximately 2,250 shots

4500psi 88cu tank, running @ 110psi (avg. 400 fps w/ .2g) = approximately 3,960 shots

Can it use CO2 as well as HPA?
PolarStar highly recommends that their system only be used with HPA due to the risk of liquid CO2 entering the Fusion Engine. If this occurred it could cause a spike in pressure which would overpower the system and cause damage to its solenoids. HPA is technically better since it isn't affected by the ambient temperature and does not have the drastic cool down affect that CO2 does.

More and more paintball stores and fields are now offering HPA to meet increasing demands and you can also have your HPA tank refilled at most scuba shops, fire houses or fire safety facilities. HPA really isn’t hard to find and typically runs about $1 per 1,000 psi to refill.

What kind of warranty is offered?
PolarStar has stated that they will be offering at least a 6 month warranty covering the PR-15 against manufacturing defects.

Will the Fusion Engine be offered separately?
Initially the Fusion will only be offered in a complete rifle to insure the first systems are properly calibrated to the AEG’s body and will perform as intended. Following very shortly after though, the Fusion Engine will be offered as a separate unit so you would be able to drop it into most any M4/M16 series AEG from many of today’s manufacturers.

What models will be available?
When the PR-15 series is released there will be three different variations available. These models consist of a PR-15 CQBR (10.5” bbl), a PR-15 Carbine (14.5” bbl) and a PR-15 Tactical Carbine (14.5” bbl w/ RIS).

PolarStar isn’t going to stop there either. They are currently working on completing their M249 variation of the Fusion Engine and their “Version 3” Fusion Engine is in the final stages of development. While PolarStar says their M249 engine will be a limited production item and available only as a drop in kit, they do plan on producing a complete rifle for their AK series.

When will they be available and how much will they cost?
PolarStar is confident that they can hit their release date in Spring, 2011 when their rifles will be available from Shorty USA and most other major airsoft retailers.

Excluding the cost of an air rig, the MSRP on the PolarStar rifles and Fusion Engine will be as follows;

  • PR-15 CQBR (10.5” bbl): $649.99
  • PR-15 Carbine (14.5" bbl): $649.99
  • PR-15 Tactical Carbine (14.5” bbl w/ RIS): $714.99
  • Fusion Engine (stand-alone V2 drop-in): $449.99

Now this might seem a little steep and right now you are probably trying to contemplate if you really need two kidneys or if your wife would notice if you sold one of the kids. However, before you go any further you should consider this for a minute. If you wanted to buy an AEG which performed even close to the upper limits of the PR-15 you would have to get a heavily upgraded AEG which is not cheap. Then, since you could not use it in CQB scenarios, you would require a second AEG. Now consider the time and money you would put into new motors, gears, batteries and pistons over the lifetime of the rifles. That six hundred and fifty bucks is looking like a pretty good deal for a rifle which could complete the role of both AEGs and its only consumable parts could be replaced for the loose change found in-between the cushions in your sofa.

The After Action Report.
The PR-15 rifles will meet and in most all cases exceed the capabilities of any AEG currently on the market. Their vastly adjustable performance and function along with the ability to perform in sub-freezing temperatures makes them ideal for any hardcore airsoft player, while their reliability and low cost upkeep makes them desirable for any airsofter with a pulse. The remote air rig might be viewed as a drawback if you have never had the opportunity to use one. However, from personal experience, it makes no discernible difference on the field and is soon forgotten.

Aside from the many technological and performance advances the PolarStar PR-15 rifles bring to the airsoft community, lets not forget that these systems are being produced right here in the United States. Considering that these rifles went from concept to production inside of a year is a major accomplishment and a testament to the determination and dedication of guys and gals at PolarStar. I can only imagine what they will come out with next.

PolarStar PR-15 EPAR CQBR
  • Operation: Electro-Pneumatic
  • Fire mode/s: Semi / Variable Burst, Semi / Full Auto, Semi only
  • Muzzle velocity: Adjustable, 300 fps to 415 fps w/ .2g
  • Effective range: 200+ feet
  • Rate of fire: Adjustable, 500 RPM to 1,800 RPM
  • Ammo type: High polished .2g - .43g
  • Hop Up: Adjustable
  • Inner barrel: 270mm
  • Weight: 4.5 lbs
  • Magazine capacity: 120 rds (M4/M16 AEG series compatible)
  • Length: 27 – 30.25 inches
  • Power source: HPA (High Pressure Air via remote air rig)
  • FCU Battery: Mini or Nun-Chuck Type
  • PSI operating range: 65psi to 120psi

PolarStar PR-15 EPAR Carbine
  • Operation: Electro-Pneumatic
  • Fire mode/s: Semi / Variable Burst / Full Auto/Semi only
  • Muzzle velocity: Adjustable, 330 fps to 450 fps w/ .2g
  • Effective range: 200+ feet
  • Rate of fire: Adjustable, 500 RPM to 1,800 RPM
  • Ammo type: High polished .2g - .43g
  • Hop Up: Adjustable
  • Inner barrel: 363mm
  • Weight: 4.8 lbs
  • Magazine capacity: 120 rds (M4/M16 AEG series compatible)
  • Length: 31 – 34.25 inches
  • Power source: HPA (High Pressure Air via remote air rig)
  • FCU Battery: Mini or Nun-Chuck Type
  • PSI operating range: 65psi to 120psi

PolarStar PR-15 EPAR Tactical Carbine
  • Operation: Electro-Pneumatic
  • Fire mode/s: Semi / Variable Burst / Full Auto/Semi only
  • Muzzle velocity: Adjustable, 330fps to 450fps w/ .2g
  • Effective range: 200+ feet
  • Rate of fire: Adjustable, 500 RPM to 1,800 RPM
  • Ammo type: High polished .2g - .43g
  • Hop Up: Adjustable
  • Inner barrel: 363mm
  • Weight: 5 lbs
  • Magazine capacity: 120 rds (M4/M16 AEG series compatible)
  • Length: 31.5 – 34.75 inches
  • Power source: HPA (High Pressure Air via remote air rig)
  • FCU Battery: Crane Stock Type
  • PSI operating range: 65psi to 120psi
Shorty USA Inc.
86 Albe Dr.
Newark, DE 19702
(302) 366-8375

Last edited by ShortyUSA_Rambo; 04-06-2011 at 09:48 AM.
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