Gas SMG Hop-Up Chambers
A gas SMG hop-up chamber is the unit in a gas blowback submachine gun, and each platform is its own part. The KWA MP7, the KSC MP9 and TP9, the Umarex and VFC MP5 GBB, the KRISS Vector GBB, the WELL G55 MP5K and the KSC VZ61 all use different chambers, and none of them share with an AEG chamber of the same silhouette. Because these are small, tightly packed guns, a retrofit chamber often comes as a kit with a matched barrel and bucking.
Also searched as: gas SMG hop up chamber, MP7 hop up chamber, MP9 hop up chamber, MP5 GBB hop up, KRISS Vector GBB hop up, VZ61 hop up chamber, GBB SMG chamber, TP9 hop up.
Fitment notes & exceptions
- The AEG version is a different part: Many gas SMGs have an AEG twin with the same outline. An MP5 AEG chamber and an MP5 GBB chamber are not the same part, and the same is true of the KRISS Vector. Check that the listing says GBB or gas blowback and names your make, not just the model of gun.
- Retrofit kits replace more than the chamber: On several gas SMGs the popular upgrade is a kit that swaps the chamber, the inner barrel and the bucking together, because the stock assembly is a sealed unit with little room to work in. These kits give the biggest gain but cost more and take longer to fit than a drop-in chamber.
- Small guns, tight tolerances: Gas SMG chambers sit in a very confined space, so a part that is slightly out of spec will bind or leak rather than simply feel loose. Buy the chamber made for your exact model and generation, and expect to check the seal after fitting.
Showing 45 of 45 hop-up units
BBT Krytac Kriss Vector GBB Hop Up Chamber Set (CNC Aluminum)
VFC MP5 GBB Airsoft Hop-Up Set V2
VFC MP5 Hop-Up Set For Umarex MP5 GBB
BBT CNC Aluminum Hop Up Chamber Set For Krytac Kriss Vector GBB SMG
VFC Original Parts - MP7 GBB Hop-Up Camber ( VGB0HOP011 / VGB0HOP021 )
![[Army Force] Hop Up Chamber [For Well G55 MP5K GBB Series]](https://cdn.shopify.com/s/files/1/0483/0642/1921/files/Untitled-1_f2e6c1f6-30d4-43c8-a22d-d5fc6d3684d4.jpg?v=1706679358#p=army-force-hop-up-chamber-for-well-g55-mp5k-gbb-series)
[Army Force] Hop Up Chamber [For Well G55 MP5K GBB Series]
Army Force Hop Up Chamber for Well G55 MP5K GBB ( AF-MP5003 )
Hop Up Cylinder (Part No. 28) For KSC VZ61 GBB
Hop Up Cylinder (Part No.91) For KSC MP9 GBB
MARUYAMA Original Parts - MP-IX GBB Hop-Up Set
MARUYAMA Original Parts - MP-IX GBB Hop-Up Set ( 02-02 / 02-03 / 02-04 / 02-05 / 02-06 / 02-07 / 02-10 )
TNT APS-X Hop Up System Inner Barrel Retrofit Kit for KWA MP7
VFC Original Parts - MP7 GBB Hop-Up Chamber Assembly ( VGB0HOP003 )
TNT APS-X Hop Up System Retrofit Kit for KWA MP7 Piston
TNT APS-X Hop Up System Inner Barrel Retrofit Kit for KSC-MP9 Adapter ( BK ) ( 14mm CCW )
TNT APS-X Hop Up System Inner Barrel Retrofit Kit for KSC-MP9 Adapter ( GD ) ( 14mm CCW )
JWI CNC Hop-Up Base Set for MARUYAMA MP-IX / MP9 GBB
TNT APS-X Hop Up System Inner Barrel Retrofit Kit for KWA MP7
T-N.T. APS-X HOP-UP System KWA-MP7 REROFIT KIT
T-N.T APS-X 220mm Inner Barrel and Hop Up set for VFC MP5 GBB
T-N.T. KWA MP7 GBB Full Hop-Up Retrpfit Kit
TNT APS-X Hop-Up System Airsoft KWA MP7 Gas Blowback Inner Barrel Retrofit Kit
TNT APS-X Hop Up System Inner Barrel Retrofit Kit for KWA MP7
T-N.T APS-X 370mm Inner Barrel and Hop Up set for KWA MP7 GBB
TNT APS-X Hop Up System Inner Barrel Retrofit Kit for KWA MP7
TNT APS-X Hop Up System Inner Barrel Retrofit Kit for KSC MP9 Version 2
TNT APS-X Hop Up System Inner Barrel Retrofit Kit for KSC MP9 Version 2
TNT APS-X Hop Up System Inner Barrel Retrofit Kit for KSC MP9 Version 2 ( 143mm )
TNT Full Hop Up 143mm Retrofit Kit Version 3 For KSC MP9 GBB Series
TNT Full Hop Up 143mm Retrofit Kit Version 3 For KSC MP9 GBB Series
T-N.T. APS-X HOP-UP System KSC-MP9/TP9 GBB RETROFIT KIT
T-N.T APS-X 275mm Inner Barrel and Hop Up set for KSC MP9 GBB
TNT APS-X Hop Up System Inner Barrel Retrofit Kit for KSC-MP9 ( 275mm ) ( BK )
T-N.T APS-X 370mm Inner Barrel and Hop Up set for KSC MP9 GBB
VFC MP5 GBB Version 2 Hop-up Set
Airsoft Website Hop Up Chamber Block for WELL G11 / KSC M11A1 Hard Kick GBB SMG Rifles
T-N.T. Studio APS-X Hop Up System Retrofit Kit for KWA MP7 Piston
Maple Leaf AST MONSTER Hopup Chamber for KWA KRISS Airsoft GBB SMG Rifles
30% Off - T-N.T. Studio APS-X HOP-UP SYSTEM HOP-UP Retrofit Kit for KWA MP7 GBB (275mm)
T-N.T APS-X 275mm Inner Barrel and Hop Up set for KWA MP7 GBB
T-N.T. Studio APS-X HOP-UP SYSTEM HOP-UP Retrofit Kit for KSC MP9/TP9 GBB (143mm)
BBT CNC Aluminum Hop Up Chamber For VFC FN M249 Series GBB SMG Rifles Airsoft
T-N.T. Studio APS-X Inner & Outer Barrel with Hopup Rubber Complete Set For KSC MP9
T-N.T. KSC MP9 GBB Hop-up CNC Retrofit KIT with inner barrel
T-N.T. KSC MP9 / TP9 GBB Full Hop-Up Retrofit Kit ( S+ Inner Barrel )
Gas SMG hop-up unit buying guide
How to pick the right gas SMG hop-up chamber
Identify the exact gun: KWA MP7, KSC MP9 or TP9, Umarex or VFC MP5 GBB, KRISS Vector GBB, WELL G55 MP5K, KSC VZ61 or a Maruyama MP-IX. Confirm the listing is for the gas version rather than the AEG. Then decide between a drop-in replacement chamber and a full retrofit kit with barrel and bucking.
Why upgrade a gas SMG chamber
Gas SMGs are usually bought for handling rather than range, and the stock chamber is often the part holding accuracy back. A precision chamber, or a retrofit kit with a matched barrel, is the change that turns a close-quarters gun into one that can hold a group at mid range.
What to check before you buy
Confirm the make, model and generation, confirm gas rather than electric, and check whether the listing includes the inner barrel, the bucking and the small parts. On kits, check the barrel length supplied against the length you want to run.
Frequently asked questions
Will an MP5 AEG hop-up chamber fit an MP5 GBB?
No. The AEG and the gas blowback MP5 use different chambers despite the shared outline. Buy the chamber listed for the gas version of your specific gun.
Why are gas SMG hop-up upgrades sold as kits?
The chamber, inner barrel and bucking sit in a very confined assembly on most gas SMGs, so brands sell them together as a matched retrofit kit. It costs more than a chamber alone but avoids mixing parts that were never designed to seal against each other.
Does a KWA MP7 chamber fit a KSC MP9?
No. They are different platforms from different makers and the chambers do not interchange. Match the chamber to the exact make and model of your gas SMG.
How many Gas SMG hop-up units does Airsoft Upgrades track?
We currently track 45 Gas SMG hop-up units across 12 retailers, starting at $4.72. A gas SMG hop-up chamber is the unit in a gas blowback submachine gun, and each platform is its own part. The KWA MP7, the KSC MP9 and TP9, the Umarex and VFC MP5 GBB, the KRISS Vector GBB, the WELL G55 MP5K and the KSC VZ61 all use different chambers, and none of them share with an AEG chamber of the same silhouette. Because these are small, tightly packed guns, a retrofit chamber often comes as a kit with a matched barrel and bucking.