Crimson GBB Hop-Up Bucking - 65 Degree - Finned

After a titanic development effort, our GBB Bucking is finally here!

Key features:

• GBB/VSR spec bucking
• 65 degree hardness NBR rubber
• Over-Chambering prevention design
• Pronounced two-point of contact pressure patch
• Alignment fin

We've been using these as our main GBBR bucking for the last few months of their development cycle to great effect. 

They've been installed into our personal replicas including the VFC KS1 and XM177, Marksman MK12 and a plethora of TM GBBPs.

From CRIMSON:

In collaboration with Waldo Dynamics and Cheffington (Ian from Firesupport UK), we spent over a year trying countless bucking prototypes, materials, and contact patch shapes to bring you the best in GBB Hop-up engineering. 
It all started with an idea; what if the bucking had a tighter initial wall to help slow down the BB to more consistently sit at the same point on the contact patch? 
After a lot of production and waiting we were finally able to test out this theory, the difference it made was phenomenal. 

The Problem

A big issue a lot of GBBRs have is something called over-chambering;
this is where the BB is pushed inconsistently and slightly past the optimal point of the contact patch when a GBB cycles. The weight and speed of the cycling mass is quite a lot to put on top of a 6mm BB and a rubber sleeve (the hop-up bucking).

How we solved it

The Crimson bucking fixes this by having a thick and durable initial opening. It takes considerable pressure for the BB to be pressed into the hop-up rubber, which helps prevent the bolt and nozzle pushing the BB too far past the contact points. 

The Benefits

This allows for a far more consistent flight path which ultimately makes your shooting experience more predictable. No more worrying if your BBs will fly slightly more left, right, up, or down. 
Paired with this we also have a contact patch with two points of contact. This shape with the valley in the middle helps align the BB totally in the middle, whilst applying more than enough pressure for even the heaviest of BBs.
We also use a material called NBR to construct the Crimson bucking. This rubber is far more durable than your traditional silicone rubber, which could easily tear during installation. 
The Crimson Bucking will be sure to last you a good while before any necessary maintenance. 


We have tested the Crimson GBB hop-up bucking in a wide range of GBBs. Below is a small list of just some of the platforms we had great success with;

• VFC AR/M4 variants (including the new EVO series)
• VFC AK variants
• VFC MP5 variants
• VFC G36
• VFC M249
• VFC PPSH
• Tokyo Marui GBB Pistols (a wide range from G17s, to Hi-Capas, to USPs etc)
• Tokyo Marui MWS M4 variants
• APFG MCX/MPX variants
• APFG XM7