Black Fox's Tricks of the Trade - The Golden Secret

[Black Fox]

Have you ever noticed that some guys guns just always seems to out gun yours? Or that they always seem to have a bit more sting to them.  There is a reason for it and I’m about to tell you why.  I’ve given some hard though about sharing this trick of the trade.  But since I don’t live in this area I really don’t have to worry about going up against any of your guns.  With that in mind I will share with you what I consider is the Golden Secret of the airsoft trick of the trade.

This secret has been around for some time but one that has not really been understood.  Because of that, airsofters in general have not paid much attention to it.  What I am talking about is matching your inner barrel with the proper cylinder to the spring and BB weight you are using.  This combination more than any other upgrade you do to your gun will determine how potent your airsoft gun is.  Done properly, you will maximize the energy and the range of your BB.  In short, you will be able to out gun most people on the field.  Done improperly, your gun will act as an airsoft vampire that will drain or prevent your BB from reaching its maximum energy potential when leaving the barrel.  I’m going to help better understand this aspect of airsoft technology.

Before we start.  First, I want you to go to this link http://www.cobraairsoft.com/default.php?cPath=79_80  and look at the Systema cylinders labeled “Type-0” thru “Type-4” or the Prometheus cylinders labeled “A” thru “F”.  You will see cylinder with holes in different sections of the cylinder (also known as ported cylinders) and some with no holes at all.  What these cylinders do, when matched properly to the inner barrel that you are using, allows the BB to reach it maximum energy potential just as it’s leaving the barrel.  I will give you an example how this work.

Let’s say you have 3 identical M-4 and all of them have a 363mm inner barrel.  The only difference is the cylinder they are using.  Gun-A is using a Systema Type-0 cylinder, Gun-B Type-2 and Gun-C Type-3.  Now let’s say all guns chrono at 400 fps with a 0.20g BB.  Since they all chrono the same, one could conclude that they would all shoot at approximately the same range.  Wrong!  Gun-B would significantly outgun Gun-A & C.  Why is that?  First let’s explore why Guns-A & C doesn’t shoot as far.

Gun-A:  The reason Gun-A doesn’t shoot as far as Gun-B is because the BB is leaving the barrel before it is reaching its full energy potential.  Because the cylinder is so long, it has way more air than the M-4 inner barrel needs.  On top of that, the piston doesn’t reach full speed until just a split second before the piston impact the cylinder head.  Because of this, the BB is pushed out of the barrel before the piston head impacts the cylinder head.  As a result, the remaining air is wasted energy and the BB does not reach its full speed potential because the transfer of energy was not complete.  The reason full cylinders are used on long barrel guns such as an M-16 is because the long barrel gives the BB more time to reach its maximum speed.

Gun-C:  The reason Gun-C doesn’t shoot as far as Gun-B is because it suffers from a vacuum problem.  Since the ports on the cylinder are too far forward.  It does not provide enough air to push the BB out of the barrel which creates a vacuum.  As a result, the BB begins to decelerate before it has even left the barrel!  This means that your gun will be shooting at shorter range than it should be.  This is what I meant earlier about your gun becoming a vampire.  It sucks the energy away from your BB.

Gun-B:  So why does Gun-B shoot the best?  Since it is a medium length inner barrel, it doesn’t need a full length cylinder.  The volume of air after the piston head passes the ported hole provides enough air to push the BB out.  Also, since there is no resistance to the piston on the first 1/2 inch of its stroke, the piston can pick-up speed more quickly.  When is does pass the ported holes, it is hitting the air faster and providing more energy.  What this does is it shoots the BB out of the barrel just a split before the piston head impacts the cylinder head, thus allowing the BB to receive the maximum amount of energy from the spring.  This translates into longer range and better performance over your opponent.  And that's why I call it the “Golden Secret”.

My description for Gun-A was creating some confusion.  For better clarification I've added this.
However, one example that I do remember the details on was a friends Tokyo Marui AK Spetsnaz that I was working on. I had an M-130 spring and a stock barrel (229 mm). When I put a full Systema Type-0 cylinder in it shot around 370 fps. When I put a Type-3 cylinder in it, it shot nearly 400fps. That was almost a 30 fps gain! (With an Excel 0.20g Bio-BB). Now when I asked my friend who worked at Systema about this. His explanation was that if you looked at the Type-3 cylinder. The forward end of the port is almost in the middle of the cylinder. This mean the first half of the piston stroke had very little resistance since the air was bleeding out through the holes. Because of the low resistance, the piston was able to gain more speed and therefore was able to impact the remaining air after the ports at higher velocity which translated to higher fps. He said when a piston travels through a full cylinder, the speed is not the same through the whole stroke. As the piston move closer to the cylinder head it picks-up speed and reaches it's maximum speed just before it completes it's stroke. So when using a full cylinder on a short barrel like the Spetsnaz. The BB has departed the barrel when the piston is only half way through it's stroke. And since the piston has not yet reached full speed. The BB is not receiving the full amount of energy that the spring is capable of providing.

I will say that if someone is using a cylinder that is providing too much air is not as detrimental to a gun that is using a cylinder that does not provide enough air. The one that does not provide enough air causes a vacuum as nears the end of the barrel which slows down the BB. One having to much air is still gaining speed as it travel down the barrel. It just doesn't receive the maximum speed that the spring can provide.



"Mini-Marine"]OK I think I see what you're getting at.

The impression I got (and I believe DMitri as well) was that given the same FPS, the gun with the proper cylinder would get more range.

What you are saying is that with the proper cylinder is more efficient and will grant higher FPS with a given spring, therefore you can achieve cap FPS with a lower power spring, which will in turn result in less wear and tear on the internals.

So how does one select the best cylinder for his gun?  

Before you start, it’s important that you know the length of your inner barrel.  If you do not have a metric measuring tape.  Crusader has provided a fairly extensive list of the length on inner barrel at this link http://www.airsoftpacific.com/viewtopic.php?t=19200

Now when you go to buy a cylinder, some brands like Prometheus, make it relatively easy by stating on the package what barrel length it is designed for.  Other brands like Systema simply state what type of gun its best use for.  But for your convenience, I’ve provided inner barrel measurements for each cylinder.

Now if you happen to have a ported cylinder lying about and you don’t know what type it is.  Here is how you can measure it.  (Note: This method does not work in KM tapered cylinders).   First, if it is attached to a cylinder head, take the cylinder head off.  Now put duct tape on the front end of the cylinder (Make sure it is water tight).  Now put a small piece of duct tape on the front end of the barrel.  Next, fill the inner barrel up with water.  Then hold it over the cylinder and open the tape so that the water empties into the cylinder.  The optimal measurement is that the water from the inner barrel should fill-up about 40% to 50% of the cylinder (45% is ideal in most cases).  Note: if you are using a ported cylinder, you measure from the forward end of the hole and not the entire length of the cylinder.  If the water fills more than 50%, then the cylinder will not provide enough air.  If it’s under 40%, then it will provide too much air.

Now someone may ask why should the cylinder have 50% to 60% more air volume than the cylinder?  This is because the air gets compressed as it is shoved into the inner barrel.

Someone may also ask, why do you give a 10% range in the measurement of the water?  There are several things that can change this equation.  As I mentioned, the volume of air in the inner barrel (represented by water in the explanation above) ideally should equal about 45% of the volume of air in the cylinder.  However, there are several variables that can change this.  The first one is the inner barrel.  You have standard barrels that measure as big as 6.10 mm to tight bore barrels that measure as low as 6.01mm.  So if you are using a super tight bore barrel you may want a little less air in the cylinder and may want to be closer to 50%.  However, if you are using a heavier BB such as a 0.25g, you may want a little bit more air.  The reason is that heavier BB moves more slowly than lighter ones and may need a little more air to push it out.  In this case you may want to lean closer to 60% air volume in the cylinder.

This brings up another point.  When you are trying to optimize your cylinder – barrel combination, it’s always best to test the gun with the BB brand and weight that you normally use in the field.

So how does one know when they have selected the best cylinder for their gun?

If one really wants to know for sure, the best thing I can think of is to buy two different cylinders and try them both.  The one that give you the higher chrono reading is the one that is the most efficient.

Well that about covers it.  If anyone has any questions, let me know.


Here's a list. Different manufacturers.  I will provide measurements for the Systema cylinders later.

Guarder Cylinder ( GE-03-01 ) G3 / M16A2 / AK
Guarder Cylinder ( GE-03-02 ) M4A1 / SR16
Guarder Cylinder ( GE-03-03 ) MP5A Series and SD Series
Guarder Cylinder ( GE-03-04 ) MP5K / PDW

Systema N-B Cylinder Type-0 ( ZS-04-16 ) M16A1 / VN / A2 / G3 / SG550 / AUG
Systema N-B Cylinder Type-1 ( ZS-04-17 ) AK47 / XM177 / SG551
Systema N-B Cylinder Type-2 ( ZS-04-18 ) MP5A4 / A5 / SD5 / SD6 / MC51
Systema N-B Cylinder Type-3 ( ZS-04-19 ) PDW
Systema N-B Cylinder Type-4 ( ZS-04-20 ) MP5K

KM TN Coated Inner Taper Cylinder for Long AEGs ( AEGS10 ) 400mm - 590mm
KM TN Coated Inner Taper Cylinder for Middle AEGs ( AEGS09 ) 200mm - 400mm
KM TN Coated Inner Taper Cylinder for Shorty AEGs ( AEGS08 ) <200mm

Prometheus Stainless Hard Cylinder ( A ) 451 - 550mm
Prometheus Stainless Hard Cylinder ( B ) 401 - 450mm
Prometheus Stainless Hard Cylinder ( C ) 301 - 400mm
Prometheus Stainless Hard Cylinder ( D ) 251 - 300mm
Prometheus Stainless Hard Cylinder ( E ) 201 - 250mm
Prometheus Stainless Hard Cylinder ( F ) 110 - 200mm

TM Full - AK47 / AK47S / M16A1 / M16A2 / M16VN / Sig550 / G3A3 / G3A4 / G3-SG1 / Steyr AUG
TM 1/3 - G36C / P90 / P90 TR / M1A1 Thompson / Sig551 / Sig552 / M4A1 / M4A1 RIS / M4 S-System / SR16 / XM133 / CAR15 / M733 Commando
TM 3/5 - MC51 / G3 SAS / AK Beita Spetsnaz / MP5A4 / MP5A5 / MP5 RAS / MP5SD5 / MP5SD6 / MP5-J
TM 1/2 - MP5K / PDW

[Ganef]

Without hard data from chronograph readings "at-range" and precise distance measurements all of this is hearsay.

There are too many uncontrolled variables involved in making a BB fly efficiently that these things could be maintained as the standard.

Also, the cylinder size chart should be a volumetric table not just a length one. Check out my post here:

viewtopic.php?f=5&t=8208

If I had the funds and the space to do it I would make an Airsoft Mythbusters and prove/disprove various garbage that is being thrown around on the net about airsoft range and energy.

[carbon14c]

If I had the funds and the space to do it I would make an Airsoft Mythbusters and prove/disprove various garbage that is being thrown around on the net about airsoft range and energy.

that would be very interesting to see!

and the whole cylender to barrel theory, I thought that was common knowledge?

[Black Fox]

Without hard data from chronograph readings "at-range" and precise distance measurements all of this is hearsay.

There are too many uncontrolled variables involved in making a BB fly efficiently that these things could be maintained as the standard.

Also, the cylinder size chart should be a volumetric table not just a length one. Check out my post here:

viewtopic.php?f=5&t=8208

If I had the funds and the space to do it I would make an Airsoft Mythbusters and prove/disprove various garbage that is being thrown around on the net about airsoft range and energy.

Ganef

I tested this theory myself many years ago and all I can say is that matching the right cylinder with the inner barrel that you are using does make a difference.  Unfortunately whatever data I recorded has long been lost.  Also, the explanation I gave above was given to me from a friend of mine who worked at Systema for many years.  I've been to Systema's factory several times and all I can say about them is when they test a product, a lot of effort goes into it.  If they make a claim that their product improves performance, I believe them.

I absolutely agree with you that having a volumetric chart for the cylinder and inner barrel is the best way to measure which cylinder is best for the type of barrel that you are using.  Unfortunately when it comes to math, calculus was never my forte. Also since volumetric information isn't readily available to your average airsofter, were stuck to just using barrel length.

I also agree with you that there are to many variables involved in making a BB fly efficiently.  The only way I was able to test to see if it worked was to test several types of cylinder on the same gun.  The guns that I tested were G3, M-4 and AK Spetsnaz.  I tested multiple cylinders on each gun.  The gun that had the most dramatic effect was on the Spetsnaz.  I had an M-130 spring and a stock barrel.  When I put a full Type-0 cylinder in it shot around 370 fps.  When I put a Type-3 cylinder in it, it shot nearly 400fps! (With an Excel 0.20g Bio-BB)

Anyway, if I didn't have a wife and two little kids I would like to join you in creating an Airsoft Mythbusters.  That would be fun.

By the way, bore-up cylinders are designed to be used with high power springs M-130 and above or guns with inner barrels that are 550mm +.  Using springs below that you won't see any real added benefit.

[Black Fox]

If I had the funds and the space to do it I would make an Airsoft Mythbusters and prove/disprove various garbage that is being thrown around on the net about airsoft range and energy.

that would be very interesting to see!

and the whole cylender to barrel theory, I thought that was common knowledge?

Only to the educated.

[Whiskey11]

My only issue with this, is that it is possible to circumvent muzzle energy limits by use of similiar methods of barrel matching, etc.  Since a heavier bb is going to be able to make advantage of a larger cylinder volume because it stays in the barrel longer due to inertia, it is possible (and there is countless studies done on this) to increase muzzle energy by using a heavier BB.

What I mean is this, we set FPS limits, some with .20's, some with .25's.  There is something known as Energy creep, we've all seen it before and it is directly related to cylinder volume.  FPS limits are set not because high FPS is dangerous but because of muzzle energy (this is the reason national ops chrono with .25's instead of .20's).  Energy creep can allow folks to circumvent muzzle energy limits, but of course, no one actually cares about that, they just see that it is under x limit with y bb and are good to go.

Anyway, the only way to truely figure out what BB weight is ideal is to measure muzzle energy, a .28 gram BB carries the most energy in my G&G M14 Veteran so I tend to use it, but I'm well below the field's muzzle energy limits  Highest muzzle energy is going to yeild the furthest range, not port matching, etc.  So long as it's close to the appropriate volume ratio (I've heard 1.5:1 to 2:1 cylinder to barrel) it's going to be ok.

The real golden secret is knowing your weapon system's strengths and limitations

[axisofoil]

I have to echo Whiskey11 on that. You want to use a bb above which you have no energy creep. Of course, you don't want to go too much higher than that or you run out of air.

Your Gun C is also errant. That's not how AEGs work... "suckback" and creating vacuums is an effect that does not occur, although the result is similar to what does happen. The bb stops getting pushed, and so has time to do those little random things that bb's like to do when they're in a barrel that isn't perfectly still. Hit the wall. Then bounce around on the rest of the barrel on it's way out. Killing your accuracy. It also creates a little more drag from this and slightly lowers your fps.

But basically... even if you were using an old school piston head that did seal both in forward travel and reverse (the ones with the air ports to push the o-ring out don't), the nozzle is disconnected long before the piston starts traveling backwards.

and Gun A has more problems than you mentioned. Besides the mentioned energy loss (which more or less happens just like you said *gold star, you can subvert this with using insanely heavy bb's. lol), you also have what is called 'blowby'. Basically the rest of the compressed air behind the bb as it leaves the barrel rushes by... all turbulent and shaky and screws with the flight path of the bb. That can absolutely DESTROY your accuracy.

Your stuff about wanting uneven volumes confuses me. You get the most energy out of the spring when you use every bit of the energy. You want the volumes matched, with a small bit of wiggle room for whatever leaks you have in your airseal. Basically, you get the most energy, and the best accuracy when the pressure behind and in front of the bb are exactly equal as the bb leaves the barrel. You have extracted all the energy without introducing any extra instabilities in the bb. Perfect.

Since we don't live in a perfect world, you should aim for this point to happen just inside of the barrel, maybe 1-2cm inside. A small vacuum in a controlled environment is more predictable than blowby, as the case may be.