
SP-RETARMS-01
Hop-Up Chamber for M4
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Pickup available at Skirmshop Spain
Usually ready in 24 hoursThe Retro ARMS design is very similar to the recent MaxModel chamber design, but significantly more affordable and, in our opinion, with better finishes and higher quality.
Hop-Up chamber for M4-type replicas.
Retro ARMS chambers feature components machined from CNC aluminum EN AW 2007 and EN AW 7075; the adjustment wheel is made of polypropylene. The adjustment mechanism is highly effective because the lever does not bend due to the materials used. Its design allows precise adjustment within a 2 mm range with 0.01 mm increments.
The chamber is 100% compatible with Retro ARMS gearboxes, but also fits standard zinc gearboxes. However, please note we cannot guarantee absolute and perfect fit.
The Hop-Up chamber is equipped with an O-ring to prevent BB drop.
The Hop-Up protrusion is integrated into the pressure lever, ensuring it won't fall out during assembly/disassembly. Optional pressure levers are available for experimental setups.
The chamber surface is anodized in black and red.
Best value-for-quality ratio in our lineup.
Pairs well with
In stock! Ships within 1-2 business days.
Complimentary shipping & returns

Hop-Up Chamber for M4
If you have any questions, you are always welcome to contact us. We'll get back to you as soon as possible, within 24 hours on weekdays.
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Shipping Information
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FAQ’s
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FAQs
Please read our FAQs page to find out more.
Do I need an account to order?
No, but an account lets you save addresses, review orders, download invoices and manage wish‑lists.
When will my order ship?
Orders placed before 15:00 CET on business days ship the same day if the
items are in stock. A tracking e-mail follows automatically.
Can I change or cancel my order?
Yes, e-mail orders@skirmshop.nl or use the contact form before 15:00 CET on the shipping day
with your order number. After dispatch, changes aren’t possible.
Do you ship outside the EU?
Yes, the shipping rates and import taxes will be calculated at checkout.
What is the minimum age to buy an airsoft replica?
Please check your own governments regulations for the minimum required age.
Don't forget to send your ID.