The Ronin 18 SPR complete upper receiver comes ready to drop onto your AEG 2.5 or AEG 3, and comprises one component of the first widely customizable AEG line, the KWA Ronin M-Series.

The RN-18 SPR is our variant of the U.S. miltary’s MK12 SPR, which was created by the Naval Special Warfare Center, Crane Division, specifically for SpecOps units with the purpose of bridging the gap between standard M4s and sniper rifles. The RN-18 upper gives you the flexibility to swap between your current AEG 2.5/3 setup and the ultimate outdoor AEG.  The RN-18 features an 18 inch barrel and a slim, lightweight aluminum KeyMod free float rail, giving you the ability to reach out and dominate your target. With the addition of any mock suppressor, you’ve got the perfect DMR.

This complete assembly comes with a solid, one-piece upper receiver and a Japanese 6.05 semi-tightbore barrel, along with our one-piece rotary hop-up, so it’s ready for a super-quick ten-second installation on your RM4 or VM4 AEG. The Ronin’s aggressive styling is complemented with a black metal flash hider, right out of the box.


  • Total Length: 673.1 mm
  • Inner Barrel Length: 457.2 mm
  • Outer Barrel Length: 482.6 mm


  • Ronin 6 PDW
  • Ronin ML Recon
  • Ronin 10 SBR
  • VM4A1
  • RM4A1
  • RM4 SR10

Weight 3 lbs
Dimensions 28.5 × 4 × 3 in

How To: Receiver Swap

Disassembly of Current Upper Receiver:

1. Push front take down pin (part #378) in from left side through the receiver until it stops.
2. Close ejector port cover (part #68) and ensure it remains in the closed position.
3. Retract the charging handle latch (part#269) and hold while simultaneously sliding the upper receiver forward and off of the lower receiver. CAUTION: Always ensure the mock bolt plate (part #M352) lays securely against the mechbox during entire disassembly and reassembly.

Reassembly of Current Upper Receiver:
1. With the mock bolt plate held securely against the mechbox and the ejector port cover is in the closed position, pull the bolt catch release away from the lower receiver and slide the upper receiver on.
2. Ensure there is no gap between the upper and lower receiver, then reinsert the front take down pin to secure the upper receiver in place.

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