Benelli M4 Extended Magazine Cap – Titanium | +1 or +3 Capacity
The Benelli M4 ships from the factory limited to 7 rounds in the tube on a standard build — or 5 rounds on an SBS. The Shell Tactical Magazine Cap Extension pushes past that ceiling without replacing your tube, modifying your receiver, or requiring a heat gun. It replaces the OEM magazine cap with a longer titanium cap that extends past the muzzle, adding physical tube length and capacity at the end of your existing setup.
Two versions are available. The +1 cap brings a standard M4 to 8+1 and an SBS to 6+1. The +3 cap brings a standard M4 to 10+1 and an SBS to 8+1 — the longest tube-fed capacity available on the Benelli M4 platform without permanent modifications to the receiver or tube.
This is a Shell Tactical original, precision CNC machined from aircraft-grade titanium alloy and Cerakoted in the USA.
Who this is for:
The Magazine Cap Extension is the right product for two situations. The first is the standard M4 owner who has already maxed out their 7-round tube and wants to push capacity further — competition shooters, home defense builds, or anyone running the gun hard who wants every round available. The second is the SBS owner who needs added capacity within the constraints of a shortened platform, where a full-length 7-round tube isn't an option.
+1 vs. +3 — which is right for you:
The +1 version adds one round of capacity with a modest extension past the muzzle. More compact, less visual profile change, still a meaningful upgrade.
The +3 version extends further past the muzzle and adds three rounds of capacity. The longer extension is the right choice for shooters prioritizing maximum capacity over a compact profile — competition use, HD builds, or SBS owners who want to maximize rounds on a shortened platform.
| Configuration |
+1 Cap |
+3 Cap |
| Standard M4 (7rd tube) |
8 rounds |
10 rounds |
| SBS (5rd tube) |
6 rounds |
8 rounds |
Why titanium:
Precision CNC machined from aircraft-grade titanium alloy and Cerakoted in the USA. Titanium is lighter than steel, stronger than aluminum, and virtually rust and corrosion-proof. Adding capacity at the muzzle end naturally shifts balance forward — using titanium rather than steel keeps that weight penalty as low as possible.
Specifications:
- Material: Aircraft-grade titanium alloy
- Finish: Cerakoted
- Versions: +1 (8+1 on standard M4 / 6+1 on SBS) and +3 (10+1 on standard M4 / 8+1 on SBS)
- Replaces the OEM magazine cap — no permanent modifications required
- Compatible with: Original Benelli M4 / M1014 with 7-round tube, and SBS configurations with 5-round tube
Colors:
- Black: custom dark gray Cerakote — can be deepened with a light coat of gun oil
- H2O: custom titanium-colored Cerakote to closely match the Benelli M4 H2O / Titanium Cerakote finish
- FDE: flat dark earth Cerakote to match OEM FDE Benelli M4s
Installation:
Remove the existing magazine cap and thread on the Shell Tactical Magazine Cap Extension. No tools, no heat gun, no gunsmithing required.
Springs:
The +1 tube includes an 8-round spring, and the +3 tube comes with a 10-round spring.
Building maximum capacity from scratch?
The Magazine Cap Extension pairs with the Benelli M4 7-Round Magazine Tube for a standard M4 build, or the Benelli M4 5-Round Magazine Tube for an SBS build.
Note: No products that increase capacity over 5 rounds ship to NJ or MA.
