HK Oversized Barrel Retaining Pin - 5.25mm

This is the barrel pin used for installing a new or replacement barrel. HK suggests using a new factory barrel pin when installing or reinstalling an HK barrel in the trunnion. Each pin is slightly oversized for trunnions that have been opended up just a tad too much. Or when reusing a trunnion an oversized barrel pin should be used in place of the standard 5mm barrel pin. A must have for any rebarrel.