The hop-up system gives the BB the backspin that keeps it flying level instead of dropping shortly after the muzzle. On a GBB pistol or GBBR it consists of a hop-up bucking that sits on the inner barrel, a chamber that holds barrel and bucking in place, and an adjustment mechanism that controls how much the bucking presses down on the BB. In this category you will find buckings, complete chambers and adjustment parts for gas-powered airsoft pistols and rifles, as well as the CO2 models built on the same platforms.
By far the most items come from Maple Leaf: hop-up buckings in 50, 60, 70, 75 and 80 degrees, the GBB buckings Autobot, Decepticon and MR (also in silicone), Super Hop-Up bucking for KSC/KWA, adjustment wheels for Glock and for Hi-Capa/1911, and hop-up chambers for Glock and Hi-Capa. Poseidon Airsoft has GBB buckings in 50, 60 and 70 degrees, while SHS, RA-Tech, King Arms, 4UAD and Dynamic Precision add buckings for the TM Hi-Capa, the G-series and INO/WA/G&P/AGM, among others. If you want to replace the whole chamber, there are CNC and aluminium chambers from CowCow Technology, AIP, Dynamic Precision, Unicorn, TTI Airsoft, Action Army and Ultimate.
What to look for
Platform and manufacturer: Hop-up parts are rarely universal. A chamber for the Tokyo Marui G-series does not necessarily fit an Umarex Glock, which is why Maple Leaf has separate Glock chambers for Marui/WE/VFC and for Umarex/VFC. WE's G-series follows Glock numbering, so the G17 corresponds to the Glock 17. Always check both brand and model in the product name.
Bucking hardness: The degree rating indicates the hardness of the bucking. Maple Leaf offers the same bucking in several hardnesses, so you can fine-tune to your setup. If the pistol runs well today, it makes sense to start with the same hardness as your current bucking.
Bucking or complete chamber: If the problem is wear, a new bucking is often enough. A CNC chamber such as the CowCow 3L for Hi-Capa or Dynamic Precision's aluminium chamber for the TM G17/18C is relevant if the original chamber is worn or has play in the adjustment.
TDC chambers: The Unicorn for Hi-Capa and the Ultimate for the ASG CZ P-10C are TDC chambers. The Unicorn is available both as a single chamber and as a set.
Small spare parts: Do not forget the small things such as AIP screws for the chamber, Action Army's O-ring for the AAP01 and WE's rubber ring for the hop-up wheel. It is often a single worn small part that causes unstable hop-up.
Who it suits
This category is for owners of a GBB pistol or GBBR whose shots are starting to spread or drop, or who want more control over the hop-up setting. If you are unsure which part fits, our workshop in Aulum, Denmark, can help with fitting and setting up.
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