Hardened inner barrel GUREN 1 6,03 AEG - 275 mm (HK416)

The length of the hop window is 6 mm, which is 1 mm longer than the standard Tokyo Marui.

For use with the R-hop bucking, square milling was used to achieve 90° at the bottom of the hop window. Conversely, the top side edges of the window are beveled to 45° to avoid damaging (cutting through) the hop-up bucking.

The outer edge of the muzzle is also bevelled. This allows for a better seating of the bucking on the barrel. Hop-up bucking are made by injection molding, so there may be a small rounding of the edge inside. If the outer edge was not beveled, there could be a problem with seating/pushing the bucking onto the barrel in that case. The bevel on the Guren barrel solves this problem and the bucking can be inserted into the correct position without any problems.