Jaeger Precision goes through the process of upgrading a VFC gas blowback rifle (URGI) to improve its accuracy by installing a 4UANTUM Magnus Pro AR Hop-Up Chamber and a new hop rubber. Starting with disassembling the GBB rifle, he removes the stock hop unit and adjuster, and installs the new components onto the inner barrel, which requires minor modification of the rubber. He talks about the unique requirements of VFC inner barrels and notes he will need to swap the barrel for one with the correct cuts in a future update.