Ackme’s Guide to the Mechanics of Airsoft – PART 1 – Hopup

PART 1 – Hopup

Hopup is your best friend and worst enemy. It gives a much greater range to your bb but it gives it very strange flight characteristics. It imparts a backspin to the bb allowing it to “float”. This gives the bb a much flatter trajectory and longer range (if adjusted right).

How Does it Work?

The barrel of an airsoft gun has a small hole in the top near the back [FIG 1]. When a BB is chambered it is pushed into the barrel and be held by a rubber bucking that goes around the barrel and has a nub that protrudes into the barrel through the hole [FIG 2]. A hopup chamber [FIG3] holds the bucking in place and has an adjustment mechanism to control how far the num protrudes into the barrel. When fired the nub on the rubber bucking catches the BB at the top and causes it to spin [FIG4].


FIG 1 – Airsoft Barrel


FIG 2 – Hopup Rubber Bucking


FIG 3 – Hopup Chamber


FIG 4 – Internal Workings of Hopup Chamber

There is a dial on the back of the hopup chamber that can be rotated to raise and lower the rubber nub in the barrel. The more the nub protrudes into the barrel the more backspin gets imparted to the BB and the farther it will rise when fired [FIG 5].


FIG 5 – Backspin Diagram

Adjusting your Hopup

There is no one right way to adjust your hopup, it’s a matter of personal preference and play style. Most players prefer to have their hopup set to a middle range where the trajectory is fairly flat with a slight rise near the end of flight [FIG6 A]. Adjusting your hopup lower gives you a shorter range but a more pradictable ballistics path, this can be useful when using optics during shorter range or CQB style games [FIG6 B]. Adjusting your hopup higher will make it harder to hit targets as the BB will "hump" very suddenly at medium range and go over your target and will have a just as sudden drop at the end of it’s flight path making it harder to hit your target, but will give you a slight range advantage [FIG6 C].

One problem with hopup is when you have to hit a target hiding behind an obsticle or at the top of a hill [FIG 7]. Having your hopop set too high will cause the BB to ‘float’ over the target or impact into the obsticle creating an area that you can’t engage [FIG 7 B & C]. In this case lowering or disabling your hopup in the field will be the only way to take out a target[ FIG 7 A].

The "Magic Bullet" Trick

In rare cases when a target is hiding behind a tree or over steep obstruction you may want to overadjust your hopup and angle your gun in such a way as the BB will ‘curve’ using the hopup. Using this trick you can curve your BB and hit targets around corners and behind obstructions that are otherwise impossible. While I’ve never heard of this techinique being called ‘cheating’ (and honsetly I’ve never seen anyone use it but me, and only in a few cases), it may be seen as bending the rules a bit, so use your best judgement.


FIG 6 – BB Trajectories when fired flat
A – Low Hopup: Flat but drops early
B – Medium Hopup: Slight rise but greater range
C – High Hopup: Rises at range and suddenly loses height


FIG 7 – BB trajectories when fired at an angle and over an obstacle
A – Low Hopup: Can hit targets low to the ground and obscured by a low rise
B – Medium Hopup: Can hit targets if they are above an obstruction but not behind it
C – High Hopup: Can hit targets at a greater distance but needs clearance at range to hit targets

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Airsoft Claymore to the Face!

Airsoft claymore from 15 feet away straight on. It actually didn’t hurt at all. A good portion of the bbs hit but they must have been going 60~80fps tops. I bought one after this but it didn’t serve me much good besides wasting time setting it up during rounds.

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Different Kinds of Airsoft Guns – Best to Worst

I keep getting asked what is the ‘best’ kind of airsoft gun to buy. Honestly, the different types of guns are pretty much the same aside from sniper rifles and support weapons. The brand matters more than the type in my opinion.

Here’s my list of pros and cons of the guns that I have used, from worst to best:

9 M14
Pros: Good exercise
Cons: Doesn’t have any advantage over smaller, lighter guns. Not many parts for it. VERY front heavy, good luck holding it up while running. Expensive. Small forward rail.

8 MP5
Pros: Very small. Lots of parts for it. Handles well in CQB
Cons: Tiny high cap mag (200rnds). Very small

7 SNIPER (Owned JG BAR 10)
Pros: Sniper kills are very satisfying. You can hit targets further and more accurately with a scope. Target often can’t hear your shot to duck (big +)
Cons: Airsoft guns aren’t very accurate at the best of times, so if you are expecting 100M head shots good luck. People often don’t know they got hit. Don’t have much of a range advantage. If someone sees you, you’re toast.

6 M249 or other support weapon
Pros: Large ammo capacity (2500~5000). Usually fits a large type battery, easy to top ammo up on the fly (just pour and go). Usually has a bipod making it easy to shoot laying down.
Cons: Very heavy to carry, it will wear you down very fast. Hard to shoot accurately if not laying down or very strong.

5 M4 (Owned Marui M4)
Pros: Tons of parts and accessories for it. Lots of configurations: sniper, cqb etc. Easy to use.
Cons: Everyone has one which makes it very boring imho.

4 G36 (Owned JG G36c)
Pros: Very easy gun to use. Lots of rails in the right places. Standard Highcap is 470rnd. Good feel. C variant is very small with stock folded in, good for CQB.
Cons: Not many parts for it.

3 AUG (Owned JG AUG Civ)
Pros: Bullpup design has very long barrel in a short gun. Easy to wind mag while shooting. Can change mag while never looking away from your sights. Great balance, it balances in the middle of the grip so you can shoot one handed easily. 2 stage trigger is very good for switching to auto on the fly.
Cons: Hard to get parts. Can’t get mag capacity over 330. All the weight is on one hand so you will look like a fiddler crab using this all the time.

2 AK (Owned JG AK47 Tactical)
Pros: Very comfortable design. Usually fits large battery internally. 600 Round basic high cap is largest available.
Cons: Small forward rail or none at all on most models. It’s a little hard to get to the iron sights with a mask on. Pretty big overall.

1 P90 (Owned Marui with hopper)
Pros: Smallest footprint of any AEG, not much more than a pistol. Sights are easy to use with a mask on. Bullpup design means fairly accurate in a small size. 2 stage trigger is very good for switching to auto on the fly. With hopper: It has a 1500rnd capacity. You can wind the hopper easily while shooting. Can top of the hopper on the fly. Hopper allows you to use a large 9.6 battery which lasts forever and gives high rof.
Cons: With no hopper the standard mags are a nightmare, they don’t fit in any basic pouch and they are hard to change. The M4 mag on the side also makes it hard to use left hand. It’s also very small and tight to hold (I got a butt extension). Strange design to get used to, but very natural when you do.

What do you think? What would you put first?

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Sniper – 2 Headshots and Pistol Kill!

Capture the Intelligence game. I get 2 clean headshots (complain all you want but if that’s all that’s sticking out, that’s what I’m shooting at). I storm the bunker after and get a pistol kill and capture the objective.

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How to: Make a Scope Camera

Directions on how to make an easy and reliable rifle (or airsoft) scope camera that can be easily made and used.

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ScopeCam Ver3 – Demo Video

Here’s a prototype for a new scope cam I’ve been working on. I’ve gotten so many requests for ‘scope cams’ and ‘how-to’ videos for making a scope cam but to be honest, the old versions were torture to use. After some deep thought I came up with this simple solution. Easy to operate, remove, and film with this solves almost all problems with the old systems. Do you have any ideas how to make it better? I’ll do a video on how to make this in a week, either as it is here or including any suggestions (which will be credited).

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Hill Assult – Airsoft HelmetcamHD

Hill assault – A small group of elite US soldiers hold a hill with three fortified fallback points. A larger force of international civilian airsoft players, ROK forces, and US forces have to storm the hill and capture it. I join the initial assault then break off to sneak up the side and manage to get one kill before being taken out in turn.

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Airsoft HelmetCamHD – Medic Control Point [2010-04-11]

A view from our squad on a control point game with medics. It shows how good teamwork and communication can change a game. We are outgunned, on the low ground, and playing against excellent players. Look at 14.06, a bb comes out of nowhere and hits me right by the camera. It was an epic sniper shot from an extreme range. I thought this round was played exceptionally well by both sides. I kept a lot more in than usual so it’s almost 15min long. I know we are yelling at Dude a lot, he was new to the game, but look at some of his plays, greatness.

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Airsoft Helmetcam – ControlPoint [2010-10-16]

This was a two hour game with no respawns. Players had to capture three points and start a timer, the highest total time at the end won the game. And yes, I’m in Canada now. I’m also indexing my videos on, I was going to do something else with it but this will work for now 🙂

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Airsoft Snipercam Test – Death to Snowman!

Testing out the quality and usability of a new snipercam rig. Unlike the last one this one is actually usable in game. It’s mounted on an M16 DMR RIS and the scope is mounted on the forward rail with the camera on the back rail. I will post a how to video on this soon, a lot of people ask me how I did the old one but it was next to unusable in game. This one is MUCH better has a number of advantages:

1. New scope allows focusing of crosshairs on the fly via a side knob
2. Forward scope mounting allows camera to be far enough forward to be able to aim properly through the camera viewfinder.
3. Using a DMR style gun allows semi auto accurate fire without having to use a bolt that would often knock the camera out of line.
4. Full auto possible for closer range
5. Clearer picture and better field of view (it’s slightly off in this vid but trust me)

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