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ACM Castellan U.D.C. Ultimate Polymer Dust Cover for M4 AEG (Capsule Style) - Black
Give your M4 AEG a sleek, modern tactical upgrade with the ACM Castellan U.D.C. (Ultimate Dust Cover) in Capsule Style! Designed as a high-performance replacement for traditional metal stamped ejection port covers, this lightweight polymer dust cover features an aggressive capsule-embossed surface that immediately upgrades your upper receiver aesthetics. Engineered for smooth opening and easy snap-fit closure, it protects your internal hop-up unit from dirt and debris while providing quick access for mid-game adjustments. Easy to install and rust-proof, it’s an essential upgrade for custom M4 builds!
£1.99
SKU
616442
Free Delivery & Returns*
SHIPPING OPTIONS
DELIVER TO
United Kingdom
United Kingdom
| TYPE | HOW MUCH? |
|---|---|
| Standard | £0.00 |
| Expedited | £4.99 |
DELIVER TO
Other countries
| TYPE | HOW MUCH? |
|---|---|
| International | £14.99 |
When building a custom M4 AEG, standard metal dust covers can look plain, easily scratch, or bent over time. The ACM Castellan U.D.C. (Ultimate Dust Cover) Polymer Ejection Port Cover brings modern firearm styling and lightweight polymer performance straight to your airsoft receiver, offering a fresh aesthetic and enhanced functional durability.
Tactical Capsule Styling & Lightweight Polymer Build The defining visual feature of this U.D.C. model is its distinct "Capsule Style" embossed pattern, giving your rifle’s receiver a high-tech, custom operator appearance. Constructed from high-density, impact-resistant reinforced polymer, it is completely impervious to rust, corrosion, and finish chipping—issues that frequently affect traditional painted metal covers. Its tough non-scratch black finish maintains its clean look even after heavy field use and repeated cycling during intense skirmishes.
Debris Protection & Easy Hop-Up Access Designed to seal tightly against your M4 AEG upper receiver, the Castellan U.D.C. prevents dirt, mud, and field debris from reaching your delicate hop-up chamber and inner barrel assembly. When you pull back your charging handle to adjust your hop-up dial, the cover springs open cleanly, giving you instant access to your settings before snapping securely shut again.
Quick & Easy Installation Engineered for maximum compatibility across standard TM-spec and aftermarket M4/AR-15 series AEG upper receivers, the Castellan polymer dust cover installs quickly into your existing mock ejection port housing using your standard spring and pin assembly. It offers a precise fit that eliminates unwanted receiver play while ensuring smooth, reliable spring-loaded opening every time.
Whether you are completing a high-end custom M4 build, replacing a damaged factory dust cover, or adding subtle tactical detail to your primary skirmish rifle, the ACM Castellan Capsule Style U.D.C. delivers style, protection, and modern polymer durability.
| SKU | 616442 |
|---|---|
| Brand | ACM |
| Weapon Category | Parts |
| Variant / Platform | M4 |
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Delivery
Our courier partners deliver from Monday to Friday, excluding Bank Holidays. We will attempt to dispatch all packages within 24 hours, although at peak times this may take slightly longer. Orders with products with two-tone service or Defence Check may take longer to dispatch.
Once the order is dispatched you will get an email with the tracking number and which courier partner it’s going to be delivered via. Any missing/incorrect items need to be reported with 48hrs of signed delivery.
Returns
Click Here to Download the Returns Form (PDF Format)
Faulty Product?! Unfortunately that is part of life but be rest assured we are here to help! Contact one of our friendly staff via phone or email. Stating what the problem is, if we can resolve the problem via phone or email great if not then they will advise how to send it back and what details we require.
Two tone
We can two tone any weapon we sell at Bespoke Airsoft. The purpose for two toning is if you do not hold a valid defense under the Violent Crimes Reduction Act (VCRA, 2006) which is to prevent the misuse of Replica Weapons, which applies in England, Scotland, Wales and Northern Ireland.
The gun will be sprayed 51% in a bright/primary color (we do only blue, green and red currently). The process of two toning currently runs at 2 working days depending on Drying Time, which is effected by Ambient Temperature and Weather. and currently no express delivery is available for this even if you select it at checkout.
The gun will be sprayed 51% in a bright/primary color (we do only blue, green and red currently). The process of two toning currently runs at 2 working days depending on Drying Time, which is effected by Ambient Temperature and Weather. and currently no express delivery is available for this even if you select it at checkout.
FAQs
1. What is a BB gun used for? BB guns are mostly used for practice shooting and training. The stronger ones (i.e. Air Rifles) can also control pests or hunt small animals.
2. Do you need a Licence in the UK for a BB gun? No, you don't need a licence for a BB gun in the UK, but there are rules. The BB Gun needs to be in two colours; one has to be a primary. All our guns are on the website as per default.
3. Is a BB gun a good weapon? BB guns, despite sometimes being seen as toys, can be dangerous. They fire pellets at high speeds and can cause serious harm, or even be deadly in some situations.
4. Can you shoot BB guns in public in the UK without a Firearm license? BB guns in the UK navigate a legal grey area. While certain models, notably low-power 'soft air' types, typically evade classification as section 1 firearms, more potent versions may require a valid firearms certificate to avoid legal repercussions.
5. Can you shoot a BB gun in your garden? You can use a BB gun in your garden under UK law, but you have to ensure the pellets don't go into your neighbour's yard, plot or land. If they do and you don't have permission, it's against the law.
6. Which UK law am I breaking if the pellets go into my neighbour's law without permission? If your BB gun pellets go into your neighbour's yard without permission, you're breaking UK laws. Specifically, the 1968 Firearms Act and possibly the 2003 Anti-Social Behaviour Act, because you may be causing your neighbours trouble or worry.
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