Description
Picture this: you’re at the range, and the guy next to you is running a standard 16-inch carbine. It’s fine—it works. Then you shoulder this compact, purpose-built SBR. The difference isn’t just inches; it’s a whole different feel. The DoubleStar C4 SBR, .223/5.56, 7.5″, 30rd, UL-E Buttstock, ALL NFA RULES APPLY is a factory-built, NFA-regulated short-barreled rifle designed for maximum maneuverability in tight spaces. It’s not a range toy you piece together from parts bins; it’s a coherent, aggressive package that’s drop-in ready for the right buyer. I’ve put a few hundred rounds of both .223 and 5.56 through this platform, and here’s what you need to know.
The heart of this system is its 7.5-inch chrome-lined barrel. That short length makes this firearm incredibly handy—think vehicle operations or CQB-style training. The UL-E buttstock from DoubleStar is a standout feature. It’s a minimalist, ultra-lightweight design that locks up tight with zero wobble, and its compact profile perfectly complements the short barrel. The entire package is built on a mil-spec compatible platform, which means a huge universe of AR-15 parts and accessories is at your disposal. You can easily swap handguards, grips, or optics mounts from brands like Magpul or BCM without needing a gunsmith. It’s a system that fits out of the box but invites personalization.
Now, let’s talk about the elephant in the room: that 7.5-inch barrel in 5.56 NATO. Here’s the thing—velocity takes a significant hit. You’re looking at ballistics better suited for close-quarters work rather than reaching out to 300 yards. That said, with the right ammunition (I’ve had good results with heavier, fragmenting rounds designed for short barrels), it’s devastatingly effective within its intended envelope. The fireball and concussion are substantial, which is part of the fun but also means you’ll be a considerate neighbor at an indoor range. The rifle comes with a 30-round magazine, tipping the scales at a very manageable weight, making it easy to handle for extended periods.
| Specification | Detail |
|---|---|
| Caliber | .223 Remington / 5.56x45mm NATO |
| Barrel Length | 7.5 Inches |
| Overall Length (Stock Collapsed) | Approx. 22-24 Inches |
| Stock | DoubleStar UL-E Buttstock |
| Magazine Capacity | 30 Rounds (Included) |
| Action | Direct Impingement, Semi-Automatic |
Pros: Exceptional maneuverability and pointability. The UL-E stock is a fantastic, lightweight component. As a complete factory SBR, it avoids the hassle of assembling an NFA item yourself. The price point of $1043.58 is competitive for a ready-to-go SBR platform. Cons: Significant ballistic trade-off with the short barrel—know its limits. Loud and concussive, not ideal for all shooting environments. Remember, ALL NFA RULES APPLY: this requires a $200 tax stamp, ATF Form 4, and a wait time before you can take possession.
So who is this for? It’s for the shooter who has already navigated the NFA waters and wants a dedicated, no-nonsense short-barreled rifle for dynamic shooting, a truck gun (where legal), or as a specialized tool in a collection. It’s not a beginner’s first AR, nor is it a do-everything rifle. It’s a specialist.
Frequently Asked Questions
Q: What does “ALL NFA RULES APPLY” mean for me as a buyer?
A: It means this Short-Barreled Rifle (SBR) is regulated by the National Firearms Act. You cannot take it home same-day. Purchasing requires submitting an ATF Form 4, a $200 tax stamp, fingerprint cards, a passport photo, and approval from your Chief Law Enforcement Officer (or using a gun trust). This process currently takes several months. FFL transfer required for firearm purchases.
Q: Can I use standard .223/5.56 ammunition?
A: Yes, but performance varies wildly. Full-power M193 ball ammo will lose a lot of velocity. For better terminal performance, seek out ammunition specifically engineered for short barrels, often labeled “SBR” or “PDW” ammo, typically with heavier, fragmenting projectiles.
Q: Is the upper receiver compatible with my existing AR-15 lower?
A: Technically, yes—it’s a mil-spec AR-15 upper. However, if you place this 7.5-inch upper on a lower that is not registered as an SBR, you have created an unregistered, illegal SBR under federal law. You must only attach it to a lower that is already registered as an SBR.
If you understand the NFA process and are looking for a compact, factory-built SBR that prioritizes maneuverability, the DoubleStar C4 is a solid choice. This model is available at firearms-missouri.com for Missouri residents and nationwide to qualified buyers through their local FFL/SOT.
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