ONYX PNEUMATIC COCKING CROSSBOW
Get the best of both worlds

The Steambow ONYX is a collapsible, pneumatically self-cocking crossbow in the tactical AR-15-type look. The first ever to be developed and built specifically for Steambow's PowerUnit compressed air technology, it is optimized for a high rate of fire and as many cocking operations out of a single compressed air bottle as possible.

Depending on arrow weight, the ONYX produces speeds of up to 330 fps and takes near to no physical strength to cock in mere seconds, producing near to no sound at all. It is operable as a fully capable crossbow also without our PowerUnit compressed air system.

The ONYX is customizable thanks to its compatibility with AR-15 parts, and its limbs are effortlessly collapsible for transport.

Arrow speed
330
fps
100
m/s
Draw weight
225
lbs
102
kg

Delivery includes:

  • Steambow ONYX pneumatic cocking crossbow
  • Scope
  • Compressed air bottle
  • Manual cocking set

Buy now

Get your very own Steambow ONYX today

How a Steambow works

Effortless cocking, near tool-less maintenance, substantially increased safety, collapsible limbs for easy transport: the Steambow PowerUnit pneumatic cocking system has it all.

Transport configuration
The limbs are folded to save space. The ONYX fits snugly in a bag, can be stowed away to save space, or carried easily with a shoulder strap.
ONYX uncocked
Since the string isn't taut, it can easily be fitted in the lock. In this position, the ONYX is absolutely safe, since at this point there is no tension in the limbs and string.
Ready to shoot
At the push of a button, the Steambow ONYX is silently tensioned and is now ready to fire.

Why get a Steambow ONYX?

COLLAPSIBLE FOR TRANSPORT

With quick-release fasteners, the limbs can be folded in and placed on the shaft in a matter of seconds. The crossbow will then be narrow enough to easily fit in a bag or pocket.

SILENT COCKING

Pneumatic cocking takes no more than a second and happens almost completely silently. Only after your shot will you hear a faint hissing sound when the air is released from the pistons.

FAST RATE OF FIRE

The string can be placed in the lock near effortlessly, which makes reloading child's play.

IMPROVED SAFETY

The shooter decides when they want to cock the ONYX. Ideally that's immediately before the shot is fired. This avoids many dangerous situations.

READY TO USE EVEN WHEN STORED

A Steambow can be stored and transported without risk with the arrow already inserted. With the optionally available disposable capsules, the ONYX can be made ready for use within seconds, even after years of storage.

VERSATILITY

Thanks to the automatic tensioning process, the ONYX can be cocked effortlessly in any position and posture, even in confined spaces, such as eg. a tree stand.

STRING CHANGE WITHOUT TOOLS

The limbs of a conventional crossbow are always under enormous tension. Without special tools and devices, it usually isn't possible to remove the string. With a Steambow, you don't need any tools at all.

LONGER LIFETIME

With a normal crossbow, the limbs are always under considerable strain and, over time, will lose strength, especially in rough conditions. Since the limbs are attached to a Steambow without pre-tensioning, this risk is eliminated.

BEST QUALITY

The Steambow ONYX is made from high-quality aluminum alloys on state-of-the-art CNC machines. All surfaces are hard-anodized and have a low-reflection coating. This guarantees high performance and a long service life.

ALWAYS READY TO USE

Even if the compressed air tank is empty, no compressor or storage bottle is available and the last capsule has been used, a Steambow can also be cocked manually with optional accessories.

Technical specifications

Weight 7.5 lbs / 3.4 kg
Length 28.5 in / 72.4 kg
Powerstroke 15.2 in / 38.7 cm
Effective range 328 ft / 100 m
Draw weight 225 lbs / 102 kg
Arrow speed 300 fps / 91 m/s

FAQ

How do I tension my Steambow completely silently?

The valve of the Steambow can allow you to cock your bow silently if it is operated very slowly. To do this, the red valve button is slowly pushed forward until the cocking process begins. With a little practice, you will be able to let the air flow into the pistons very slowly, making the cocking process completely silent.

If, on the other hand, the red valve button is pushed forward in one go, the priming of the pressure chambers in the Power Unit will be very fast, causing noise from the pistons and limbs in particular, which might be disturbing or unwanted under certain conditions.

What's the easiest way to supply my Steambow with compressed air at home?

In our experience, a small storage bottle, such as a used diving tank, is the simplest solution. The small compressed air cylinders required for Steambow can be filled directly from such a storage cylinder using a separately available adapter. A single storage bottle with a volume of 5 to 10 liters contains enough compressed air to allow you to shoot with your Steambow for months. This storage bottle itself can be filled in paintball shops, diving shops or at specialized dealers.

Do I have to regularly service or care for my Steambow?

A Steambow, like any other crossbow, requires regular care and maintenance. As with a traditional crossbow, you need to regularly check the string and treat it with a string wax. The string retainer at the limb-tips to which the string attaches should be waxed or greased before each use to keep friction as low as possible. All moving parts should be lubricated regularly with a drop of oil. Disassembly is not necessary. In the case of the trigger, simply allow some oil to drip into the trigger mechanism where the trigger exist the receiver inside the trigger-guard and where the string retention engages with the string on top of the barrel. All bare or black metal parts made of conventional steel, such as the original screws and fasteners of the basic crossbow, need a thin film of oil to prevent corrosion. All steel parts of our PowerUnit are made of stainless steel and do not need additional protection.

Our PowerUnit is essentially maintenance-free and will work for years without any problems. Nevertheless, we recommend unscrewing the piston cap, pulling out the piston and greasing the sealing rings at least once a year. The 4 O-rings in the valve should also be greased at the same time. To do this, remove the valve pin from the main valve. More details can be found in the instructions for use.

How many shots can I get from a bottle?

The number of possible shots depends on two things: First, how much energy is required to cock your bow and, second, how much energy you have available.

The energy requirement per cocking depends mainly on the draw weight of the crossbow - the more draw weight, the more energy is required to cock your bow. For this reason using our "Power Reduction" system that only tensions the limbs to partial strength therefore enables significantly more shots. This effectively reduces how tensioned the limbs are and therefore how much energy is transmitted to the arrow when you fire. However, less energy also means less kinetic energy for the arrow, which then flies more slowly, less far and has less penetration.

The available energy is stored as compressed air in paintball bottles. There are basically two types - those made of aluminum with a 200 bar storage pressure and bottles made of carbon fiber with a 300 bar storage pressure. Furthermore, the compressed air cylinders come in a range of volumes. The smallest bottles have a volume of approx. 0.2 liters, the largest bottles (which can easily be mounted on the steambow) have a volume of 1.1 liters. The bigger the bottle, the more energy is stored.

Our experience shows that with the smallest bottle available on our strongest steambow you can get about 5-6 shots are possible at maximum power. After that there may not be enough pressure to fully tension the limbs. However, 5-6 shots is more than sufficient for use in hunting - for training or the like, however, the bottle would have to be refilled often.

For regular training with your steambow, we therefore recommend using a larger bottle, ideally made of carbon with 300 bar and a volume of 1.1 liters. This bottle can also be conveniently carried in a pouch on your belt using a hose connection to the steambow. Then you have well over 50 shots available, even at maximum shot power.

What is a "hose connection" and what do I need for it?

This hose connection is called a “Mamba-Line” in paintball and is available in almost every paintball store and online shop. A Mamba-Line consists of a connection piece for a paintball bottle with a screw valve, a hose that is usually twisted in a spiral and a quick release coupling for connection to a paintball filling nipple. Higher quality Mamba lines also usually have a vent valve on the side of the quick coupling. An adapter should also be included in the order for your Mamba-Line in order to be able to attach the hose connection directly to the air connection of the steambow.

So you need: a mamba line, a larger compressed air bottle (from Steambow) and a bag to comfortably carry this paintball bottle.

You now have several options:

First, you can screw the supplied adapter directly to the air connection of the Steambow and attach the quick coupling of the Mamba-Line to it, or you can attach the Mamba-Line to the filling nipple of a small paintball bottle. In this case, the small paintball bottle is attached to the steambow and the hose connection is also attached to the small bottle. The small bottle then serves as an adapter, so to speak. You can do this at any time if the small bottle no longer has enough pressure. Unfortunately, it is not possible to refill the small bottle completely this way, because the Mamba is supplied by a larger paintball bottle and therefore only has an output pressure of 60 bar. We expressly recommend that the Mamba Line only be operated at the pressure specified by the manufacturer defaults - and normally that is 850 PSI or 60 bar. The storage pressure of the simple aluminum bottles is 200 bar - therefore, filling is not possible.

How do I use a hose connection on my Steambow?

The bottle connection of the Mamba-Line usually has a knurled screw to operate the bottle valve. Make sure that this screw is screwed out as far as possible - i.e. screwed counterclockwise. Now the Mamba-Line is screwed onto the larger paintball bottle. As soon as the quick coupling of the Mamba-Line is attached to the steambow or to the filling nipple of a smaller bottle, you can put the hose connection under pressure. To do this, screw the knurled screw on the Mamba-Line to the right, i.e. clockwise, as far as possible. You will hear a faint hissing sound and the hose will move with the incoming pressure. The hose connection is now functional.

To disconnect the hose connection, proceed as follows: First, the larger paintball bottle on the mamba is deactivated. You do this by unscrewing the knurled screw on the mamba line to the left, i.e. counterclockwise. The bottle is now deactivated and does not supply any more air. However, there is still a lot of residual pressure in the hose - too much to be able to simply unplug the Mamba-Line. There are several ways to vent this residual pressure, depending on the equipment of your Mamba-Line. But even if your Mamba-Line does not have a vent valve, venting is easy: Operate the main valve of your Steambow and set it to "tension", rather than all the way forward. There is not enough air in the hose connection to fully cock it, but the limbs will move. With every further "tension attempt", the movements become weaker until there is almost no pressure in the system. Now you can simply unplug the hose connection using the quick coupling.

Important: Steambow is an Austrian company operating under Austrian law. It is the buyer’s responsibility to make sure the products they order from Steambow are legal in their country and can be shipped there without any issues arising from customs and other restrictions. Steambow GmbH assumes no liability for difficulties arising from the legal situation in the buyer’s country.