A hop-up system is one of an airsoft gun’s most important components. A good hop-up unit will ensure the maximum range possible for your setup.
This article aims to explain the basic function of hop-up, parts of a hop-up unit, and how to adjust a hop-up unit in order to maximize efficiency.
WHAT IS HOP-UP?
Hopup is an effect that utilizes the same mechanics as the physics phenomenon known as the Magnus Effect, in which a cylindrical object with backspin relies on air resistance to resist the effects of gravity.
In simple terms, backspin is applied to your BB to give it more range.
This effect is controlled by a hop-up unit, which uses a little arm to push down on a bucking (or packing), which then translates to backspin on the BB, as seen in the diagram below:
WHAT IS A HOP-UP BUCKING (PACKING)?
A hop-up bucking, or packing, is a small rubber slip that fits over your barrel. This component goes directly between the hop-up unit itself and the BB, as the hop-up effect is applied to your BB using direct contact with the bucking or packing.
Buckings are usually made of rubber with varying hardness. Although softer buckings allow a better air seal and finer adjustment, harder buckings used for higher velocity setups offer better durability over prolonged use. When buying a bucking, information is usually provided by the seller on the material hardness and recommended velocity (measured in feet per second) range.
Figure 2: Standard AEG Bucking
Figure 3: 1911-Style Gas Blowback Pistol/VSR-10 Sniper Rifle Bucking
WHAT TYPES OF HOP-UP UNITS ARE THERE?
Although the basic principle of all hop-up units is the same, there are numerous designs to achieve this magical backspin effect.
Dial Style: This style is commonly found in most stock M4 AEG’s (Figure 4). It relies on mini gears to move an arm downwards, which applies pressure to the top of the bucking. A variation of this style can be found in most Gas Blowback Pistols (see figure 5).
Rotary Style: This style can be found on higher end AEG’s and aftermarket upgrade hop-up units (Figure 6). Despite achieving the same effect as dial style, it is often more consistent, convenient, and allows for finer hop-up adjustment. A variation of this style can also be found in select Gas Blowback Pistols.
Slider Style: This style is most commonly found on AK AEG’s (Figure 7) and stock Sniper Rifles. Instead of a dial, it relies on a sliding mechanism to physically push down the hop-up arm, which applies pressure to the top of the bucking.
TDC Style: TDC, short for Top-Dead-Center (or Top-Down-Center for some), is most commonly found in aftermarket hop-up units, especially in Airsoft Sniper Rifles. This style allows direct downward pressure on the hop-up bucking, as some stock slider style hop-up units result in off-centered application of hop-up, resulting in side-hopping and BBs curving off to the side. The TDC style can also be found in some Non-Blowback Gas Pistols. Figure 8 below depicts an aftermarket TDC unit on a sniper rifle with a mod that allows for external, tool-less adjustment.
WHAT ARE NUBS?
A hop-up nub, also called a tensioner, is a small piece of rubber or plastic that sits in the hop-up arm. This small component determines the contact area that the bucking touches the BB with. Different nubs usually directly correspond with various types of hop-up systems.
WHAT HOP-UP STYLES ARE THERE?
There are numerous types of hop-up styles that can achieve different goals, depending on what kind of bucking and nub combination you use.
The most common type of hop-up system uses a small roll of rubber to apply pressure to the top of a bucking. Figure 9 shows a standard M4 AEG bucking and nub. Note the small, cylindrical nub as pictured below.
Flat Hop uses a rubber nub with a flat contact surface, standing in contrast to the standard round nub. This allows for more contact surface on the BB, which can translate to more consistent hop and better range. Flat Hop is usually considered the no-hassle younger brother of R-Hop. However, it is not without its own quirks and complications. Figure 10 depicts flat hop nubs designed by Maple Leaf.
R-Hop uses a small piece of rubber directly integrated into the barrel. This patch directly contacts the BB, rather than using the bucking to do so. This allows even more contact than flat hop, but requires certain amounts of expertise and fine-tuning to get it just right.
Styles of hop-up aren’t just limited to these three, however. There are many mix-and-match systems based on different nub and bucking combinations, such as S-Hop, H-Hop, and M-Hop, only to name a few. However, all achieve similar effects depending on what is needed of them.
HOW DO YOU USE/ADJUST HOP-UP?
Adjusting your hop-up unit will control the amount of backspin applied to your BB. Adjusting hop-up appropriately will unlock the full range potential of your airsoft gun. In order to do this, an appropriate trajectory must be achieved, as seen in the graphic below:
