Reservoir Mods XL – Precision Airgun Moderators
Reservoir Mods XL – Precision Airgun Moderators - is backordered and will ship as soon as it is back in stock.
Delivery and Shipping
Delivery and Shipping
Delivery
For most UK addresses, orders are sent via Royal Mail First Class or DPD for larger or heavier items.
Delivery typically takes 1-5 working days, depending on the service used. Many orders placed before 12 noon arrive the next working day (Monday-Friday).
Orders over £50 qualify for free shipping to most UK addresses.This excludes shooting products that require Royal Mail 18+ Signed-for Delivery.
Remote Locations (Highlands, Islands & Northern Ireland)
Deliveries to Scottish Highlands, offshore islands, and Northern Ireland may require alternative courier services due to higher delivery costs in these regions.
Small parcels under 350g are sent via Royal Mail and qualify for free shipping if the order value is over £50.
Larger or heavier items are shipped via UPS, and shipping charges will be calculated at checkout, but in most cases it will cost £9.99.
Delivery typically takes 2-5 working days, depending on the service used.
Returns
If you are not satisfied with your purchase, we have a 30-day returns period. In the first instance, please contact our support team via email: support@3leggedthing.com
Royal Mail Deliveries
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Reservoir Mods XL – Precision Airgun Moderators
Description
Description
Two Profiles. Same Performance.
Wavy Profile (RSV1)
A flowing, organic exterior with subtle contouring. RSV1 offers a softer visual language while retaining the same internal geometry and suppression performance as RSV2.
Chamfered Profile(RSV2)
A sharper, faceted design with clean chamfers and a more technical aesthetic. RSV2 is visually bold but mechanically identical inside.
Profile choice is purely about looks and feel — performance remains unchanged.
XL design for precision and ultimate quiet:
- 8-chamber modular design
- 20.2 cm (7.95") length
- 36 mm (1.4") diameter
- Internal volume: 95 ml
- Increased airflow management for maximum suppression
- The XL versions offer greater internal volume for shooters who want the quietest possible report, while the standard models prioritise balance and handling.
Why choose Reservoir Mods?
Because effective sound suppression isn’t about brute size — it’s about controlling air intelligently. Reservoir Mods are tuned to manage pressure smoothly, reducing sharp crack without over-damping the system or upsetting the rifle.
Quiet. Controlled. Deliberate.
PLEASE NOTE: These products will be shipped using a method that will require a signature, and proof that you are aged 18+.
As mods are an 18+ product, they require Special Delivery and aren't eligible for free shipping, even on orders over £50. Sorry!
SAFETY WARNING: These products are designed exclusively for use with airguns and are not intended for use with firearms. Any modification, adaptation, or use on a firearm may result in product failure, serious injury, or death. 3 Legged Thing accepts no liability for any damage, injury, or loss arising from the misuse or modification of these products.
TERMS & CONDITIONS: See our T&Cs Section 12 here or Important Legal Information below.
Specifications
Specifications
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Material
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Specs
IMPORTANT LEGAL INFORMATION
IMPORTANT LEGAL INFORMATION
Airgun moderators are not a regulated or licensed product in England, Wales, or Northern Ireland and may be purchased without restriction in those jurisdictions.
Customers purchasing from outside England, Wales, and Northern Ireland are solely responsible for ensuring that the purchase, importation, and ownership of these products complies with all applicable laws and regulations in their jurisdiction.
3 Legged Thing accepts no responsibility for any delays, seizures, restrictions, enforcement actions, or other consequences arising from a customer's failure to comply with local laws or regulations.
By placing an order, you confirm that you have verified the legality of purchasing, importing, and owning this product in your jurisdiction and that you are legally entitled to do so.
CUSTOMERS IN SCOTLAND
To comply with Scottish legal requirements, you need to supply proof that you have a valid Airgun Licence. To do this, please provide your licence number, and expiry date in the Add Order Note field in your Shopping Cart before checkout. You can find this bottom left, just above the orange CHECKOUT button.
RESERVOIR MODS XL 8-CHAMBER DIAGRAM
STAGE 01 - ENTRY & FIRST EXPANSION
High-pressure gas enters immediately behind the projectile. The bore opens into a precision-calculated volume, triggered the first and largest pressure drop.
STAGE 02-07 SEQUENTIAL VORTEX
Air expands and vortexes within each successive chamber. Compressed wool gaskets strip residual energy between every stage - natural, dense, acoustically selected.
STAGE 08 - FINAL ATTENUATION
By the 8th chamber pressure is reduced to near-ambient.The exit report is a fraction of the original muzzle energy - clean and controlled.
STAGE 09 - UNDISTURBED FLIGHT - BY DESIGN
The projectile leaves the bore ahead of the propellant gas. By the time that gas is vortexing through the chambers, the pellet is already in free flight — completely clear of the turbulence. The Mod manages the report. It never touches the trajectory.
Chamber Absorption Technology
THE MATERIAL
THAT DOES THE
REAL WORK
Every chamber in the Reservoir Mod contains a precision-cut wool/polyester gasket disc. They are not packing material. They are not incidental. At 277 kg/m³ — nearly four times the density of high-performance acoustic panels — they are one of the most deliberately specified components in the system.
The Density Advantage
Standard acoustic fibrous materials operate at densities between 8 and 80 kg/m³. The Reservoir Mods gasket discs are specified at 277 kg/m³ — a figure that places them in an entirely different performance regime.
At this density, the resistance to airflow through the gasket matrix is extremely high. Energy that cannot move freely is converted to heat. That conversion is the mechanism of attenuation.
The Blend
Wool and polyester contribute different physical properties to the same task. Wool fibre has a natural crimp that creates a highly tortuous internal structure. Polyester adds dimensional stability, ensuring each gasket holds its geometry under repeated cycles without compacting or shifting.
The result is a gasket that performs consistently across the service life of the product, not just when new.
Wool fibres perform most effectively at densities above 500 Hz — the frequency range where surface friction increases and more energy is dissipated as heat per unit of material.
The mechanism is viscous friction. As flow moves through the gasket matrix, vibrating molecules rub against the irregular interstices of the fibre network. That motion converts energy into thermal energy.
Mechanism: ISO 9053 / Delany–Bazley model for fibrous porous materialsThree mechanisms. One gasket.
Flow forced through the fibre matrix loses kinetic energy to viscous drag.
Wool's natural crimp creates a structurally complex internal path that lengthens the effective route and multiplies opportunities for energy dissipation.
The cumulative result of friction and tortuosity is heat: energy is progressively converted and dissipated into the gasket mass.
Performance is often discussed in terms of chamber count or overall volume. Those are meaningful numbers — but the material inside the chambers determines how much work each stage does.
A low-density gasket passes flow relatively freely. A high-density gasket forces that flow to surrender energy before it exits each chamber. At 277 kg/m³, this disc is specified to extract maximum attenuation at every stage.
Gasket Specification
The Features:
What's in the box?
Haven't really had the chance to put it to the test as of yet. Have shot 20 shots through it. It is whisper quiet, looks amazing on my Wolverine and build quality is very good. Also it didn't alter my zero. Would definitely reccomend.
Love it! Nice and quiet and still getting great groupings with my AAS510 so no clipping, very happy indeed.
Absolutely fantastic and delighted— hoping that a blue reservoir
Works great 👍 and modular design to suit your rifle
Great bit of kit this is my second one
Looks great, haven't tried it yet as I dont have a muzzle adaptor yet..Great craftsmanship on the unit.
Fantastic build quality, first class machining. Not as quiet as standard Weihrauch mods which was a bit disappointing for the price. But they look great.
It works exceptionally well on a Barra 250z doing 920 with 25gr. Pellets. I intend to use it with the new Northtac Qilin BP-X 28” Bullpup doing about the same fps with 34gr pellets. Thanks for an excellent product.
really quiet much better than the other 2 i have
Super quiet. 2 dB less than an Impulse Air and 4 dB less than a Fox tune. Too bad taxes and shipping added 45%.
Absolutely fantastic only got a small back garden and it's made my gun silent I can sit and enjoy plinking without disturbing my neighbours best I have tried beautifully made and finished
Brilliant
Super,,works extremely well and very fast delivery. Great communication. I highly recommend.
Excellent mod, even looks nice; equally as quiet as the weihrauch, using it on my favourite gun and its whisper quiet 10/10
Brilliant moderator. Brought two thinking if i added a couple of baffles it would help with more noise reduction . Didn't make any difference. But still very quiet and extremely accurate. And a thing of beauty to the eye
Brilliant, super quality moderator and super quiet, looks good too!
Exceptionally good
Well made and so so quiet!
The back that it can be lengthened or shortened to suit individual needs is as far as I’m aware the only moderator that offers this
Brilliant!
Great product its hard to tell yours from the one i have on my other rifle and that one was twice the price so thanks
Its a great looking mod and beautifully finished.
One of the quietest mods I have tried on a sub12 air rifle.
Being modular means you can add and remove sections to get the perfect tune.
Now they just need to make one thats wider, around 35mm would be great.
Super quality. Love the way I can add/remove sections to fine tune my rifle; with one section removed it is the most accurate moderator I have used on my Anschutz 9015 and it is still whisper quiet.
Look forward to trying it out on my Daystate Red, Black and Alpha wolves. You were right; it was well worth the wait while you battled the supply chain issues.
Congratulations guys, this one is a gem!
Well made and does what it says on the box.
Think my rifle is marginally more accurate with the moderator on.
Need to do lots more testing yet though, only used once.
Beautifully made, fits well and is very quiet. Unfortunately it opened up the groups on my TM1000 so I’ve gone back to the Air Stripper, but the Mods XL will be used on my other rifles!
Great to have a moderator that I can adjust the length of to suit my rifles. The finish and qualitity is outstanding for the price point. Well worth the wait!
Can't be beaten,I would buy another if they were not sold out.
Excellent mod thanks
On my HW 100 KT… quiet 👍👍👍
The best moderator for accuracy, price, adjustability/ tune-ability and sound absorption. I'm a big fan.
Excellent service and product.
Fantastic kit
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