both of those v3 and v4 on the LDT HK416 are fantastic, having said that The one shot in HK416 v4 will likely be extra stable due to the mosfet mounted. equally versions offered by AKgelblaster will come with metal https://kkgelblaster.com/collections/best-sale/products/electric-m416-hk416d-assault-rifle-gel-ball-blaster