Guides and Tutorials

UPGRADE GUIDE | FPS

| 4. FPS |

| 4. FPS |

A flow valve is located within every MK23 magazine, this flow valve is responsible for the release of gas from the magazine gas reservoir up in to the nozzle of the pistol which is then used to propel the BB from the gun. The flow valve is pretty basic and mostly identical between the TM and clones versions of the magazine, but does have some slight differences in size (such as the valve key size and the size of the vent holes). Whilst the size of the vent holes can determine the speed of which gas flows through the valve, it is the size and position of the hole that determines the volume of gas that flows through the valve.

A high flow valve or a flow valve that has been modified in such a way that it acts as a high flow valve is a valve that allows the maximum amount of gas to be released from the magazine in to the nozzle per shot.

What does it do?
A high flow valve is designed to allow a larger than standard amount of gas volume and pressure to be released from the magazine reservoir up into the pistol nozzle. With release of higher pressure and volume, the nozzle is able to deliver that pressure and volume on to the BB within the hop up chamber. The result of this is BB that departs the barrel at a higher FPS and often better shot per shot consistency due to the same amount of gas being released each shot. 

High flow valves can be purchased as an aftermarket upgrade from various manufacturers that each have their own way to provide a more efficient release of gas from the valve, however a standard valve can be modified at home quite simply us a file or rotary tool. The "High Flow Valve" mod requires the user to remove a beam from each side of the valve that forms one of the 4 vent holes, resulting in the valve having 2 larger venting holes instead. With the valve correctly placed in the magazine, with the vent holes facing upwards towards the gas flow port, the "High Flow" effect is achieved.

Why do you need it?
High flow valves are generally not needed by the majority of MK23 users as their pistol is already shooting at an FPS limit they are happy with without needing to modify the flow valves of their magazine. However, due to the relative simplicity of replacing the flow valves of a magazine valve with an aftermarket part or performing the high flow valve modification yourself, this mod is a sure way to quickly upgrade the FPS (as much as 10 - 25 FPS) of you pistol when using a high flowed magazine.

High flowing your magazines can prove to be a cheaper alternative to increasing the length of your inner barrel to gain additional FPS, or used in combination with a longer inner barrel to reach a desired FPS limit.

 

This mod is also worth considering for users who are simply trying to get better shot consistency by having a more stable FPS per shot.

How do I modify/install it?
Depending on the brand of magazine, a TM or WE style valve key will be needed for disassembly of the valve without potentially damaging the valve key slot. You can attempt to removed the valve using an appropriately sized flat head screwdriver at your own risk. This guide assumes the user will modify their flow valve themselves.

You can perform the High Flow Valve mod by following these steps:

  1. Ensure the magazine is empty of gas.

  2. Place the magazine face down so that the BB channel is facing a flat surface.

  3. Locate the release valve on the rear of the magazine opposite the feed lips.

  4. Make sure that the release valve knocker can be depressed fully in to the release valve body (the circular bit in the center of the release valve).

  5. Using a TM or WE valve key, place the valve key so that it locks in to the available valve key slot (two lines either side of the release valve knocker).

  6. Turn the key CCW to loosen and remove the valve from the magazine body. 

  7. Place the magazine to one side.

  8. Inspect the flow valve and locate the two holes in the valve opposite the valve key side.

  9. Using a file or rotary blade, cut the wall between each hole at the lower and upper side of the hole wall.

  10. After removing the the wall of the first hole, the hole should now be much larger.

  11. Repeat the removal of the wall on the opposite side for the remaining hole.

  12. You should now have two larger holes with a single wall "pillar" on each side.

  13. Sand and neaten up the holes as needed, ensuring that any metal residue is cleaned up.

  14. Return the flow valve back in to the magazine and tighten in a CW direction using the valve key.

  15. When making the final turn to tighten the valve, ensure that the valve key slots align horizontally across the width of the magazine. This is to ensure that the flow valve hole is position so that it faces upwards and towards the nozzle port.

  16. Fill the magazine and ensure no leaks are present, tighten the valve if leaking occurs.

This mod is applicable for all MK23 models. Additional information is available here.

PART: Inner Barrel

As mentioned elsewhere in the Upgrade Guide, replacing the stock inner barrel with an aftermarket upgrade can have a considerable impact on the FPS output of your MK23 (in addition to the Accuracy and Range). The features of the inner barrel can determine the output FPS in either direction. For example, a shorter and wider bore inner barrel can decrease the FPS as the gas spends less time in the barrel and expands more quickly due to more available bore space, with more room for the gas to pass by the BB; whilst a longer and tighter bore barrel can increase the FPS as the gas spends more time in the barrel and has less bore to expand in to and less room for the gas to pass by the BB.

 

Changing the size and features of your inner barrel can be a quick and easy way to meet FPS requirements for your play-style or field.

What does it do?
Replacing the stock inner barrel with a modified or upgraded inner barrel will effect the FPS output of the MK23, whether it is a decrease or increases is dependent on the specifics of the barrel. Referring to the Barrel Length examples from the "Accuracy" Barrel Upgrade, it's easy to see how the length of the barrel alone can change the output FPS result. For example, when not taking in to account the propellant used or bore size used, we can assume the following based on community results:

- A barrel shorter than 133mm will be below 330 FPS on 0.20g BB's

- A barrel longer than 133mm will exceed 318 FPS on 0.20g BB's

- A barrel longer than 150mm will exceed 350FPS on 0.20g BB's.

- A barrel longer than 220mm will exceed 400FPS on 0.20g BB's

- A barrel of 310mm will reach 420/430 FPS on 0.20g BB's.

- A barrel longer than 310mm may see a small increase to FPS, but as the length increases the FPS will start to decrease as the barrel length increases and reaches a point where any gain is lost and the gas loses pressure and expands.

As you can see, the FPS output generally increases as the barrel length also increases, and the opposite can be said when decreasing the length of the inner barrel. As some fields have strict guidelines on FPS limits, such as 300 FPS for indoor use and 450 FPS for outdoor Semi Auto use, changing out the barrel to meet the limits of a specific field is a very useful option to keep your MK23 in play.

When using a tight bore (6.01mm - 6.05mm) inner barrel, gas has a harder time to pass by the BB and therefore imparts more speed on the BB for a longer time whilst it remains in the barrel. For this reason we can assume that tight bore barrels will provide a positive FPS gain.

When using a wide bore (6.08mm and up) inner barrel, the distance between the BB and the bore wall is larger, resulting in gas being able to expand quickly and for gas to slip past the BB more easily. This can result in reduced gas pressure and less speed being imparted on the BB the longer it spends in the barrel.


Why do you need it?
Although there are other means to increase or decrease the FPS output of your MK23, none are as simple, consistent or effective as changing the features of your inner barrel. Having multiple barrels of differing lengths and bore sizes can allow you to change from indoor to outdoor, meet close range engagement distances or improve the use of a carbine kit for a DMR style role; all at the change of a barrel.


How do I modify/install it?

You can perform the Inner Barrel mod by following these steps (Skip step 6 to 10 if you have already drilled out the outer barrel):

  1. Remove the slide from the body.

  2. Remove the hop assembly/barrel unit from the slide.

  3. Remove the dust cover from the assembly, removing the spring beneath the dust cover at the same time.

  4. Remove the center screw / pin from the outer barrel.

  5. Slide off the outer barrel from the assembly.

  6. Place the outer barrel in an upright position in a vice or another means of securing the outer barrel in preparation for the use of a drill.

  7. Using a 8.5mm to 9mm drill bit, slowly drill away material from the outer barrel with the drill bit positioned directly in the center of the outer barrel "bore".

  8. Continue to drill through the material until the drill bit passes through cleanly to the the other side of the outer barrel.

  9. Using the new inner barrel, ensure that the entire width of the inner barrel can pass through the out barrel smoothly.

  10. Clean up the outer barrel for any burrs or sharp edges.

  11. Place the outer barrel to one side and continue disassembly.

  12. Remove the two assembly body screws.

  13. Separate the two assembly body halves with the barrel kept in place and laid flat and exposed on a surface.

  14. Remove the hop arm from the assembly.

  15. Remove the inner barrel with the hop rubber attached.

  16. Remove the old hop rubber from the barrel.

  17. Replace the old inner barrel with the new inner barrel.

  18. Replace the old hop rubber with the new hop up rubber if available, ensuring that the rubber fits securely to the grooves of the new inner barrel and that there is no bulging present.

  19. Apply the "Teflon Seal" Mod (see below in this guide).

  20. Return the barrel and hop rubber to their slots in the hop up assembly, and ensure that the rubber and barrel fit snugly.

  21. Return the hop arm to the assembly.

  22. Return the two assembly body halves together.

  23. Return the two assembly body screws.

  24. Apply the "Inner Barrel Spacer" Mod to prevent any barrel wobble from potential tolerance issues after drilling.

  25. Return the outer barrel to the assembly.

  26. Return the center screw / pin to the outer barrel.

  27. Return the dust cover spring and dust cover.

  28. Return the hop assembly to the slide.

  29. Return the slide to the body.

MODIFICATION & PART: High Flow Valve

 
 

PART: Feed Lip Gasket Shim

The rubber gasket which directs the flow of gas from the magazine flow valve up in to the nozzle assembly where it sits flush with the nozzle to deliver gas is naturally a very important piece of the puzzle to ensure a good air seal and consistent FPS. By adjusting the height of the gasket position in the magazine, it is possible to manipulate the effectiveness of the seal between the gasket and the nozzle by changing the distance between the two. The closer the gasket to the nozzle, the higher the FPS; the further the gasket to the nozzle, the lower the FPS.

What does it do?
Shimming / adjusting the rubber feed lip gasket to increase or decrease the contact distance of the nozzle and gasket can reduce or increase the FPS of your MK23. This mod can be performed in several ways, but each option will achieve the same end result and see an increase or decrease of FPS in your MK23. The three main options to consider are as follows:

- Adding a laser cut metal shim below the rubber gasket in the magazine gasket slot to raise the height of the rubber gasket. These shim's are designed specifically for the TM or Clone magazines and are available from several retailers.

- Swapping the TM rubber gasket with a Clone rubber gasket to increase the height of the rubber gasket in a TM magazine (as the clone rubber is taller), or swapping the Clone with the TM rubber gasket to reduce the height.

- Using a razor / sculpting blade, remove some material from the bottom of the rubber gasket to reduce the seated height of the rubber gasket in the magazine. This is a permanent solution, and should only be attempted as a last means to perform this mod.

You can also find alternate ways to increase the height of the rubber gasket, such as stretching a thin o-ring around the metal square mounting or fashioning your own shim to sit below the gasket, but the results of these methods are an unknown and are left to you to experiment with.


Why do you need it?
On average, you can expect to see a gain or deficit of between 15 to 50 FPS depending on the contact between the rubber gasket and the nozzle. If you have exhausted other options provided in this guide to increase or decrease the FPS of your MK23, this mod is a worthwhile consideration.

How do I modify/install it?

The feed lip rubber gasket can be accessed in the following steps:

  1. Place the magazine upright so that the spring is facing you.

  2. Lay the magazine down so that the right side of the magazine is against the surface.

  3. Using a small screwdriver or hole punch, locate and tap out the pin directly beneath the feed lip.

  4. (Optional) You may need to lay the magazine down the opposite way to step 2 if the pin is mounted in the opposite direction, this is because the pin has a thread on one end and will not pass through the wrong way.

  5. With the pin removed, pull down the magazine follower slightly to relieve pressure on the feed lip.

  6. Lift up and remove the feed lip.

  7. Perform one of the available options for this mod (adding a shim or swapping out the rubber gasket)

  8. Taking the feed lip, pull down the magazine follower slightly and place the feed lip over the rubber gasket and press down to ensure a secure and flush fit.

  9. Continue applying pressure on the feed lip to keep it in position, then replace the pin from the same end that it was removed from, ensuring the threaded side of the pin faces outward.

  10. Tap the pin back in to the magazine. Check that all areas appear flush and test the magazine.

For more information, please see the following installation video (For 1911, but applies to MK23), here.

 
 

An often overlooked aspect of the MK23 by users looking to increase or decrease their pistols FPS is the propellant that actually powers the pistol and gives the BB's leaving it a measure of velocity in the first place.

The MK23 magazine can function with most of the common gases / propellants used in the airsoft community, however there are some restrictions to keep in mind.

Due to legal restrictions in Japan, Tokyo Marui is required to ensure that their airsoft replicas do not exceed a velocity of .98 Joules (325fps) using factory components. Due to this restriction, the Tokyo Marui MK23 magazine was designed with a pressure release valve that would open and vent gas from the magazine in the event that the pressure within the magazine would mean that the velocity of the shot with stock components using that gas would exceed the legal limit.

 

As a result of this, users of the Tokyo Marui MK23 have found that the magazine pressure release valve vents (leaks) when they attempt to use higher pressure gas than the recommended HFC-134a (such as Green Gas / Propane / Red Gas or higher) and required modifying the pressure release valve before the magazine would accept the use of higher pressure propellants. When the Tokyo Mari MK23 was reproduced by other airsoft manufacturers (clones), the pressure release valve was removed from the magazine design to allow the magazine to accommodate the use of higher pressure gas without modification. 

When considering the use of HPA (High Pressure Air) to power your MK23, you must modify the pressure release valve on the Tokyo Marui magazine or use a clone magazine to prevent leaking.

Changing the propellant used within the MK23 magazine can dramatically effect the output velocity and therefore the FPS of the pistol with little to no effort, and in doing so can also save you quite a bit of money to run the gun.

What does it do?
Generally each gas / propellant offered or used within the airsoft community has a different storage pressure when stored within an airsoft replica magazine, and in a MK23 magazine to be specific. In very simple terms, that pressure when released in to the workings of the pistol converts to a measurable velocity as it throws a BB out of the barrel which we tend to capture with the use of a chronograph. By using a propellant which is stored at a higher or lower pressure in the magazine, it is possible to change the base output velocity of the MK23 as the force behind the BB becomes less or more powerful and capable of accelerating the BB.

Whilst this guide will not cover all the different brands and types of gases, the basic types and their names are listed below to give you some direction when looking to increase or decrease the FPS capability of your MK23. For compatibility reasons, the achievable FPS of each propellant type is not provided.

HFC-134a, Blue Gas, Duster Gas: Ideal for low FPS, rated at ~75  to ~96 PSI.

Generic Airsoft Green Gas: For Medium to High FPS, rated from ~104 to ~140 PSI.

Pure Propane: For High FPS, rated from 134 to 143 PSI.

MAPP, Yellow Gas: For High FPS in winter seasons, rated at ~174 PSI (lower during winter use).

HPA: For Low or High FPS in all seasons, HPA regulators allow for custom setting of PSI.

As a note, airsoft gases sold as "Green Gas" should be considered to be Propane with lubricant additives.


Why do you need it?
After considering the different PSI limits of each propellant type (you may need to do additional research outside of this guide) and how it may translate to a higher or lower FPS for your MK23, it's easy to look at changing to a more or less powerful propellant type to set the baseline FPS for your MK23's before upgrading or downgrading other parts in the replica. You should also consider what is affordable and available to you and identify whether you can achieve a similar performance from your MK23 by changing the propellant that you use for a cheaper alternative. Most MK23 users are avid fans of pure propane for its affordability and power.

How do I modify/install it?

For the most part, changing the propellant is just a matter of selecting and purchasing a different propellant off a store shelf. However when considering higher PSI gas alternatives, you may need an adapter to allow the use of specific gas bottle types, such as a propane adapter provided by several airsoft manufacturers. When considering HPA, a full conversion system will be required to allow the use of HPA with a MK23 magazine.

For some additional reading about airsoft propellants, this link and this link covers the subject quite well.

MODIFICATION: Propellant Upgrade

MODIFICATION: Valve Spring Removal

 

Unlike the TM magazine, all clone magazines feature a flow valve that includes a return spring to help the flow valve return to a closed position after releasing gas in to the nozzle. The retention provided by the spring helps the valve return to the closed position faster, which prevents gas from entering the nozzle.

Without the spring in place, flow valve returns to a closed position less quickly, therefore allowing more gas to enter the nozzle.

What does it do?
By removing the flow valve retention spring, the flow valve is forced to close naturally under the pressure of the the gas as it moves through the flow valve; this then results in the valve reaching a closed state more slowly. The benefit of the flow valve reaching a closed state less quickly is that more gas is able to enter the nozzle per shot which directly translates to additional FPS per shot.


Why do you need it?
Removing the retention spring does not cause any adverse effects barring the need to possibly push the release valve spring inward when empty so that it correctly finds a seated position when being filled, once filled requires no manual adjustment. Users have observed an increase of between 10 - 25 FPS after removing the retention spring which makes it considered a free and very easy to install FPS increase.

How do I modify/install it?

As this modification only applies to the clone magazines, a WE style valve key will be needed for disassembly of the valve without potentially damaging the valve key slot. You can attempt to removed the valve using an appropriately sized flat head screwdriver at your own risk. This guide assumes the user will modify their flow valve themselves.

You can perform the Valve Spring Removal mod by following these steps:

  1. Ensure the magazine is empty of gas.

  2. Place the magazine face down so that the BB channel is facing a flat surface.

  3. Locate the release valve on the rear of the magazine opposite the feed lips.

  4. Make sure that the release valve knocker can be depressed fully in to the release valve body (the circular bit in the center of the release valve).

  5. Using a WE valve key, place the valve key so that it locks in to the available valve key slot (two lines either side of the release valve knocker).

  6. Turn the key CCW to loosen and remove the valve from the magazine body. 

  7. Place the magazine to one side.

  8. Remove the flow valve retention spring from the flow valve.

  9. Return the flow valve back in to the magazine and tighten in a CW direction using the valve key.

  10. When making the final turn to tighten the valve, ensure that the valve key slots align horizontally across the width of the magazine. This is to ensure that the flow valve hole is position so that it faces upwards and towards the nozzle port.

  11. Fill the magazine and ensure no leaks are present, tighten the valve if leaking occurs.

 

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