What is hop-up?

Hop-up is system in airsoft replica to the back-spin put on airsoft pellets and BBs to increase their range.

Hop-up devices apply backspin to the projectile reducing the air pressure on its top side. This causes the plastic pellet to fall less over a given distance than it would without the spin applied, extending the effective range of the weapon without increasing velocity.

In airsoft guns, this is usually implemented as a projection (called a bucking) into the path of the projectile, on the top of the barrel.

The rubber is located on the beginning of the barrel, which has special cutouts to accommodate the bucking and nub. This allows for the hop arm to push the nub down onto the bucking and into the inner barrel and connect with the BB.  Different platforms have varied means accessing the hop up; in order to access hop up adjustment in most AEGs you need to pull the charging handle back in order to open the dust cover revealing adjustment wheel for hop up. This is a standard location of hop-up adjustment for all M4 and M16 airsoft replicas.

Having the right hop up adjustment on your airsoft gun will maximize its effectiveness.

Airsoft Hop-Up Adjustment Steps:

  1. You will need a big safe open area at least 50ft distance down range and a torso size target.
  2. When safe, fire 2-3 shots at your target and see where the BBs are going. 
  3. If you’re BBs are doing exactly like figure A (going down). You have to turn your hop-up up. Look at your gun’s hop-up device and try to find an arrow with word saying “up.” Turn it that way for your BBs to go up.
  4. When your BBs are going up like on figure B, you have to turn your hop-up down. It should be dialed against/opposite from the arrow that says “up.”                          
  5. Repeat 3 and 4 while properly aiming at your target, fine tune your adjustment by dialing your hop up unit as little as possibe.                                
  6. You have it right once your BBs go very slightly UP and then maintain its line then slightly go down, almost like a straight line and hit your target. This is the best setting for your hop up. If your target is too close, you will not see the effect of your hop up and you need a longer distance target.

Hop-up Types:

Hop-up Rubber/Bucking and Nub
Most players know that the hop up rubber and nub set up is far more important when it comes to improving accuracy and range. To quickly clarify:

Hop-up Rubber – This is a rubber bucket which is inserted on the end of barrel. It serves 3 purposes:
·             Holds the hop up unit together with the barrel.
·             Provides hop on the BB by contacting it through the bulge inside.
·             Creates airseal due to bucking lips leaning against air nozzle.

There are softer and harder versions which differentiate in their durability and somewhat performance. Softer means usually better grip, but it does not last as long. Also cheap quality buckings will freeze up during cold weather and will provide less friction.
Hop-up Nub is what presses on the bucking to allow for backspin. This part is very important too, as it allows for compression when a bb passes through. If it were to be made out of plastic, or other hard surface, the bbs would not be able to get through as easily and it would wear the bucking quickly. Many people change original nubs in order to have a specific shape or more surface area to hop the pellet better which we’ll cover in the flat hop section. Generally, most nubs come in a package with a bucking – double check when purchasing.

Degrees of hop up

There are variations of hop up in their thickness and softness of rubber material. This is very similar to car tyre compounds. You can decide whether you want softer hop which will have better traction and stronger effect on BBs or you can choose harder and more reliable version which will have more durability. 
Low degree are soft, they range around 50-60 degrees
Medium are about 65-70/75 degrees.
And hard are 75-80 degrees and up. 
Another aspect people should look at is the temperature reaction of said hop up buckings. The thickness does make a difference, mainly whether the bucking will or will not partially freeze up in cold weather. However, softer buckings will warm up quicker during gameplay through friction with fired bbs; partially, because some companies use compound specific material to perform better in cold weather. With those, you will not have to choose lower degree bucking just to counter weather issues.

Recommended Buckings
Prometheus Purple
G&G Green
Maple Leaf 
Tokyo Marui
When purchasing any of the above, make sure to double check what replica types they are compatible with in the description of the product. Generally speaking, there are two types of inner barrel cuts that divide into “AEG” and “Sniper & Pstol”. So just simply make sure you’re not buying a sniper bucking for an M4.