12G Dark Storm Steel 3

12G Dark Storm Steel 3" Shotgun Cartridge

High Performance 3" Precision Steel with Bio-Wad

Building on our ultimate performance Quad Seal design, the Bio-Wad Gen II is a new full cup wad utilising the same 100% environmentally safe, cutting-edge material. 

Manufactured in-house by Gamebore, the Bio-Wad takes all the benefits of the Quad Seal technology with its incredible gas seal allowing Gamebore’s exclusively blended powders to burn cleanly for maximum pressure, and incorporates a new and unique cup section for steel shot.

The Dark Storm Precision Steel with Bio-Wad cartridges have a high-tech design featuring four petals with unique 45 degree overlapping edges for complete barrel protection on pellet setback, plus ribbing for reduced surface friction and extra overall barrel protection. 

The high strength of the Bio-Wad material means we can load high-performance steel cartridges for guns with the appropriate Fleur de Lys proof marks. 

All cartridges should be stored at room temperature in a dry location. Adverse temperatures may affect performance. Do not expose to extreme temperatures.


Our precision steel shot is manufactured to ensure absolute consistency of size and sphericity and produces a non toxic alternative to lead shot with no compromise on results. 

Dark Storm Precision Steel is loaded with our exclusive Alliant double-base powder to give outstanding downrange energy and all-weather performance meaning you won’t miss using your usual lead shot. 

The Bio-Wad is now in brown to minimise visual impact in the field throughout the biodegradation period. 

Shotgun proof and choke recommendations for each load:

  • 1/35gms *High Performance Steel Proof Shotgun with Fleur de Lys stamp. CIP regulations state no choke restriction however we strongly advise Half Choke Maximum.
  • 2/35gms *High Performance Steel Proof Shotgun with Fleur de Lys stamp. CIP regulations state no choke restriction however we strongly advise Half Choke Maximum.
  • 3/35gms *High Performance Steel Proof Shotgun with Fleur de Lys stamp. CIP regulations state no choke restriction however we strongly advise Half Choke Maximum.

    *Steel MPS Velocity calculated at Muzzle and falls within MAXIMUM CIP Momentum.

Steel Shot Sizes

1 4mm
2 3.81mm
3 3.5mm

Quad Seal™

Exclusive 4 Ring Gas Seal






For reduced surface friction and improved barrel protection

Wad Petals

Cut at 45° to ensure full barrel protection on pellet setback



Quad Seal

Quad Seal

The exclusive Quad Seal®. Delivering a level of ballistic consistency not previously achievable thanks to its revolutionary four-ring design. The Quad Seal reduces recoil, increases striking energy and is 100% environmentally friendly being fully degradable.

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The Bio-Wad® is a full cup wad utilising cutting-edge water soluble material which is 100% environmentally safe. Incorporating all the benefits of the Quad Seal with the addition of a new and unique cup section. The Bio Wad has ribbed petals with unique 45 degree overlapping edges, giving complete barrel protection.

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Precision Steel

Precision Steel

Soft steel shot to CIP regulations from one of the world's leading manufacturers for exacting standards. Reliably consistent in its sphericity and size for outstanding patterns.

Alliant Powder

Alliant Powder

Exclusive to Gamebore in Europe. High technology, cutting edge double base (nitroglycerin) powders allow us to develop and manufacture high performance loads without excessive perceived recoil. Alliant powders feature in our small gauge loads, high performance heavy weights, premium steel and non toxic cartridges. These loads simply cannot be replicated by using single based propellant.

CX2000 Primer

CX2000 Primer

The most highly consistent and reliable primer available. We use CX2000 Primer throughout our range of shotgun cartridges to give the shooter the utmost reliability and confidence.

HD Case

HD Case

High density polymer plastic case designed to perform in our premium, high performance range. Delivering easy loading and smooth ejection from a case made specifically for these demanding loads.


3" Case

A 3" (76mm) case for use in guns with 3" chambers where case length is critical for optimum performance.

D 7.9

D 7.9

Shot with a Density of 7.9 gram/cm3

30 Day Infield Degradation

30 Day Infield Degradation

Bio-Wad is injection moulded at Gamebore using a 100% environmentally friendly and hydro soluble material which is approved and accepted by estate managers and landowners, thanks to its quick degradation time and reduced visual impact in the field. The Bio-Wad degrades over 10x faster than any traditional fibre wad on the market. The material is water soluble and fully biodegradable, conforming to the CEN 13432 European standard for compostability.

Technical performance
Velocity x Distance

The following graph shows the relationship between Velocity (MPS) and Distance (M) for the shot selected from the table below.

Load gms Shot Size WAD Length mm Muzzle Velocity FPS Velocity MPS V1
35 1, 2, 3 Bio-Wad 20/76 1460 425

Designed & Developed by Gamebore for Gamebore

How the Bio Wad Works

Designed and developed by our R&D division, the environmentally friendly Bio Wad is specifically designed to give complete barrel protection and maximum performance when using steel shot.

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"For Guns who are sceptical about using steel we have no hesitation recommending and endorsing Dark Storm Precision Steel Bio Wad 3’s. They are hugely effective on our high birds. We have shot over 80 days with the majority of our Guns using steel since September and with one exception, all have been thrilled with the results! Most Guns have converted to using steel on other shoots, not just at Warter. Well done Gamebore on a super product."

Frank Croft, Head Keeper at Warter Priory Estate

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