Tuning your Hop Up the Correct Way

[crasstoe]

Credit for this guide goes to Tackett off of Airsoft Society. (I made 1 tweak at the end)


So, I'm seeing a lot of threads on subjects like: "what 750mm barrel will give me the most accuracy." and so forth.

The real sad part to these questions is, that typically the person asking is putting this brand new $60 plus barrel into a totally stock hop up assembly. This is not the way to improve your accuracy or range. The first and very first thing a person should be doing before turning to the barrel, is fine tuning the hop-up. Only after the hop is tuned should you even consider turning to the inner barrel. If someone is unhappy with their AEGs accuracy, my advice is always to tune the hop-up, use the gun for a while, if you are unhappy with the performance still, then start turning your attention to the inner barrel or other items. So this guide is being written to serve as a starting point for those wanting to increase their accuracy.

Step 1: organize your workspace.
Before starting on any project, always start with a neat, clean, organized, workspace. Place down a towel to keep the small parts from rolling around. Like so:

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Step 2: organize your tools.
You will need:
A naked utility knife blade.
A small sheet of aluminum foil
Superglue
A dremel with cone grinder attachment
Dental floss
Teflon tape
Permatex anaerobic gasket maker.
Lube of some kind
A solid nub. (SCS, hnub, or even a piece of wire.)
A standard squishy nub

Step 3: Prepare the Bucking
Now, why exactly are we messing with the bucking? Simple, consistency and shape. There is one thing on the inside of these buckings that will, overtime, lead to a inconsistent hop up. A little mound of rubber. To get to this thing, you have to turn the bucking inside out. Now, most of the time, that's easier said than done. Especially with the softer buckings that will tear if you aren't careful. The easiest way to do this is to use your inner barrel and unroll it. It doesn't matter how you do it, just flip it inside out, unharmed.

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See the little mound now? We need to get rid of this thing. There are a number of ways, I use a dremel, because patience is not one of my virtues. But however you do it, be careful and sand it down out of existence. It should look like so:

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Well, we are left with a uneven surface that's been roughed up by our removal process. We need a nice clean surface to make contact with the BB. We can achieve this by removing the locking line, much the same way that we removed the mound. Very carefully. It should look like so:
BEFORE

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AFTER

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Next we need to cut off about 5mm or more off the end of the bucking. We do this because when we go to seal it, the added material of floss and tape will stretch out the bucking, and make it impossible to get the c-clamp on. Use your naked blade, and chop it like so:

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Now, use your blade and slice a small V at the end of the bucking, pointing at the clean area we want the BB to contact. This is so, when we turn the bucking right side out, you can tell which side is up.

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Turn the bucking slightly right side out, except for the last 1/4 of it. Like so:
Your bucking is now tuned and ready for install.

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Step 4: install the Bucking
We are going to be installing the bucking in a way that there is no possibility of a air leak anywhere. The first thing you want to do, is run a small bead of permatex around the end of the barrel, between the nozzle side and the hop window. Like so:

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And after the hop window, like so:

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Place the bucking on being very careful not to smear the bead of permatex, making sure your V notch points at the hop window. So you know your good section of rubber is where it needs to be.

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Unroll the rest of the bucking, again, being careful not to smear the permatex all over the place.

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Now, take a small length of dental floss and make a loop on the end:

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Wrap the rest of the floss over the bucking pulling it tightly. Thread the tag end through the loop and pull the other tag end so that the loose end gets pulled under the tightly wrapped floss.

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Cut the loose ends. The finish product should look like so:

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Now, I always wrap a small amount of Teflon tape tightly around the end, being careful not to cover up the indents for the clamp to seat in. Usually two turns is all I do. Finished bucking should look like this:

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Step 5: install the Chamber

This part is tricky. Use copious amounts of lube and slowly, carefully twist the chamber over the bucking, making sure you end up with the "V" pointed at the location your hop arm is going to go. Make sure it doesnt wrinkle up, and gets installed correctly. You should end up with a finished product like so:

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This part takes time, and if you have too much floss and tape on the end of your bucking, it will make it even harder, if not impossible. So if at first you don't succeed, try try again. Keep at it, start over if you have to. It's not easy, but it will go. I promise.

Step 6: Tune the hop arm
Where we removed the internal mound, we need to backspace the nub to make up the difference. I do it this way, but it doesn't matter how you do it.

Take a standard squishy nub, and slice it a little over halfway with your razor.

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Put a dab of superglue on the hop arm and glue the little slice of stock nub to the arm:

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Now take your solid nub, whatever the case may be, (In this case it's a SCS.) and glue it to the stock rubber that's glued to the arm, like this:

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Let this thoroughly dry. You may have to shave the ends off slightly so that the arm articulates smoothly.

Now, with many hop ups, the adjustment dial is extremely loose. To the point that, the bbs hitting the nub, can actually through your adjustment off. Let's fix that by shimming the arm, so it fits tightly into the chamber and is not so easily moved. This will allow finer adjustments, and keep it from being inadvertently thrown off.

Take a small piece if aluminum foil, spread some super glue on it, and press the hop arm against it.

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Let the glue dry and slowly peel off the excess foil.

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Install the arm and turn the dial, keep adding layers to the arm until you get the tightness desired. I like mine so tight that I have to turn the dial with a pair of needlenose.


Step 7: Final adjustments
Now that everything is installed, look inside the barrel with the hop fully on and make sure that the nub is centered in the barrel. If it is not, twist the barrel holding the hop chamber steady, until the nub is centered correctly.

Run a bead of superglue around the barrel and end of the hop chamber. Then ram home the brass collar.

Finished:

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Now, your hop chamber is about as fine tuned as you will get it, and doing this mod correctly will enable you to squeeze every last inch of range and accuracy as possible with a semi-stock chamber. If this does not satisfy you, then it's time to start down other avenues such as swapping barrels


I have just done this to the G36, amazing results, however I did one thing differently. Since I do not have a H-Nub I made one using a spare hop nub and glued the two together;

[evilpanda88]

Re: Tuning your Hop Up the Correct Way

Nice one, really informative, may have to give this a try

[crasstoe]

Re: Tuning your Hop Up the Correct Way

It is well worth doing. My first attempt the BBs would fly like a snake moving through sand, LEFT RIGHT LEFT RIGHT LEFT RIGHT... I hadn't cut the nub in half properly and had too much of a V going on. When you get it right the effects really are something.

The reason this is in the General Section is because this could apply to ANY hop, not just AEGs.

[crasstoe]

Re: Tuning your Hop Up the Correct Way

A pic to show the results on the hop end of the inner barrel for those wondering what the home made H-Nub can do;



Considering this is using the home made H-Nub I am very impressed, and doesn't have too much of a curve like the actual H-Nub you can buy. I think I have done a better job than the actual guide too

The Rubber used is a Soft SHS White one inside a 5KU CNC Hop chamber mated to a 6.03 490mm TBB for those interested.

[crasstoe]

Re: Tuning your Hop Up the Correct Way

Also a note about this, you WILL lose some FPS. I lost 30 fps to this mod, as the increased contact area on the bb does take some of the oomph from the shot, the remedy a bigger spring