Outside(?) the Gearbox: How to Fine Tune a Hopup Unit. 

AAA battery will turn the bucking inside-out quick, little hot tip lol

Excellent presentation. You obviously spent a lot of time setting it up & it certainly showed. I'll give you a 9 out of 10. It would be very helpful in future vids if you showed quick examples of the work you did off camera instead of cutting right to the finished product. This includes cutting off the bump from the bucking & inserting the eraser into the hop up unit. You don't need to show the whole process but at least how you started each task. Besides that I thought it was very well put together. Lots of very good stuff here.

Hey I know you posted this video forever ago but I just want to say I loved it. It was not only super useful but extremely clear as well. Thanks for making it!

Thank you for this great tutorial! After 5 years, still the best one available!

I was debating wether to flat hop myself or not to. But after seeing this it, I made up my mind and did it and glad I did. I think a gained at least 50 ft to my range, with the barrel that came with my gun, just in time for a big game this weekend. This is by far the best tutorial on how to do this from what I've seen. Awesome job, I am now a sub of yours!

This video and your shimming video singlehandedly helped me save my G&G Firehawk.

Just finished the above operation on my home built M4 CQB (230mm barrel). Very happy with the results:I used teflon tape instead of dental floss; with the improved air seal fps on a .2 it bounced from an erratic 315-325 to a very consistant 380-381.Range on this AEG was very poor before; with the flat hop mod now in place its easily my most accurate, consistent and longest range M4 type AEG; Never seen any of my AEGs with such a nice fluid and long lasting flight path; unfortunately I don't really have a good way of gauging the range but it really seemed like a good 60-70% range increase. Looking forward to try this on my other AEGs, especially my S&T SVD and home built SPR MK12 (DMRs) which already are pretty accurate with decent range. Thank You AirsoftTech, good mods!

Awesome! I've been wondering on how to this for a while but kept forgetting to look it up. Keep up the awesome work!

Thanks again for another great, informative and useful video. I just bought my first airsoft m4 about 2 weeks ago and already upgraded the barrel to a 6.02 Tight Bore and a Pro Max Me Pro Hop Up Unit. I am looking forward to applying your video on Air Seal to to it next.

Did this on my g&g cm16 srl and what a difference! Bb flies perfectly flat, I saw a huge increase in range and accuracy as well!

Wow fantastic in depth vide keep up the good work u my good sir have earned yourself a sub

Great video. I followed the directions and had great results with my Lonex L4-02. Thanks very much.

this is awesome tech tips! keep up the good work while I do my first flat hop mod. :)

Five years later I have found you! Thanks for the advice.

great vid! very informative. i learned alot

awesome.. did three aegs with ur videos.. each with fantastic results! 120ft hitting a plam size target

This actually worked great for my CM0.39 [ak47] stock replica. Just used an eraser that was lying around, cut straight pieces out of it (which is pretty difficult with a small cutting blade) and after leveling the hop up arm, I used quick glue to stick it to the arm. I also used a dremel to smooth out the surface of the stock bucking and put it correctly onto my 6.08 barrel (So putting the untouched side of the bucking over the hole in the barrel). The overall performance in accuracy, precision and range were greatly boosted. (And this was my first attempt...) Maybe you're thinking what if I put a precision barrel, a new bucking and a new hop up unit in a cheap brand? I've have to warn you for the headaches and wasted time you're gonna put into it. My Cyma and many others are not compatible with a lot of hop up units (for example; retro arms) or any retail product for that matter. If determined, watch more youtube videos or do your research. Thinking back now, I would of rather used this method again.

I just ordered the Firefly flat hop nub so it goes right into the hop up arm arch thats already there but it all nice and flat. I love mine so far

negative airsoft are you seeing this pipe thread tape, dental floss and erasers.. lol

Doing this right now to my SR-47 build. The hopup unit in this gun is so freaking proprietary that I don't want to grind down the hop arm. Instead I'm using a Modify Flat Hop bucking with a slightly modded flathop nub that comes in the kit. I added a bit of pink eraser to the bottom of the nub to increase the amount of hop. I was almost maxed out when trying to lift even .28g BBs. I lie having the dial in the center position as opposed to one extreme or the other. Using the Teflon tap on the end of the bucking is getting me a nice bump in FPS using that Modify flat hop kit. Those buckings are a bit loose.

2019 and these are still usefull

awsome vid going to do this to my lancer tactical.

My God:gun replica makers, do everything to make complicated mechanics, so we can not copy them, in 90% of the cases!!! 😢. So, it is good to have you and others to lend a help.

I just recently purchased my first gun. A KWA cqr mod 2. I am running an 11.1 lipo and switched over to deans connectors. Everything else is stock on my gun. Would it be worth it to do this mod to my gun? Will I see the increased accuracy and range with all of the internals being stock still?

great videos dont understand how you only have 6000 subscribers

Great vid.

Can’t wait to do this on all 6 of my guns thank you

+TheAirsoftTech Thank you for the explanation, i have a G&G bucking and a stock Cyma bucking, should i make a flat hop out of them, or should i wait 1 month and order another g&g?

I have a prowin hop up unit should i still do the shaving of the arm and eraser nub if i have a Modify Flat Hop Bucking with the nub it comes with.

the eraser makes it amazing

Does any know how much more range I would get from a gun that is firing at about 343fps (UK Max 350fps) through a standard G&G Hop up unit. At the moment I'm getting about 140 to 150 feet. Thanks

Would I need to match the nub size to the hop up window, or barrel window?

Awesome breakdown and explanation and presentation!!!

Could I use like a razor blade or something else sharp to cut off mound and line? I tried once with sandpaper just messing around with my stock CYMA bucking, but the sandpaper made the surface really uneven and rough. And I don't have access to a dremel, so I'd have to use something else.

Can i make a flat hop out of a rotary madbull hop up chamber with a madbull blue bucking? do you recomend other configurations? thanks

Wait why not use a sanding attachment for the dremel? Wouldn't a cutting attachment but up the bucking?

Can I install a flat hop without sanding it ?? I could form the eraser to fit in, or?

Wouldn't you be able to use a sanding but for the mound and lock line shaving?

Funny how an eraser and dental floss will make you gun better than from the manufacturer

Good video i am going to try this on my g&g m14 ebr and probably upgrade to an 6.01 barrel would you recommend that for a sniper platform?

nice tutorial (+ explanation!), gonna use this and try it myself =) question: how do you check air seal of the hop-up chamber? I'm having some fps inconsistencies issues, checked cylinder, nozzle etc and they are fine. Just don't know how to check hop-up chamber air seal =S

So basically, with your mod, you don't need to fill the window of your barrel like other g/r flat hops?

how do i do this to my g36 hopup?

Thanks so much for the video. After spending a few hours tooling around I was able to mod and install a flat hop on a Cyma 005 M4 using the stock Hop up chamber, a Madbull 6.03 tightbore, a green G&G bucking and a piece of rubber stopper as the nub (it's a little more stout than eraser but not by much). I'm now having issue adjusting the hop up and keeping it in place, the hop up gears and wheel seem to be under an undo amount of stress and won't stay in place after dialing. The resistance on the hop up arm seems a little tough but the height of the nub is only about 3.5mm Any suggestions? Thanks a ton!

Hey man, first off great video. Really contemplating doing this setup in my stock G&G MK18 M4. Beginner tech here, so I'm looking to get my gun shooting like I've seen others have. You know, it landing where your optic is actually aiming. With a stock gun, I was thinking of adding a few things to improve the gun. Stating with a tightbore barrel. See how it changes the gun. Then, add a G&G green bucking. Test and review, and then follow up with your flat-hop setup here. Thoughts? Any tips on where to start when improving a gun?

Tip put the bucking in hot water for 5mins. Before turning inside out. This will make the rubber pliable,

Whip the bucking...use the floss to whip it, 4-5 wraps and it's completely sealed.

My gun is flat hoped with a ProWin hop up unit, firefly namazu flat hop nub, and promi purple bucking and it shoots like 175 feet.

I'm getting out to 250ft with out the flat hop modification I also have a 509mm barrel. If I get the Madbull shark hop up working and change my madbull tight bore barrel to a steel angle custom or lonex barrel, I should be hitting around 300ft with pin point grouping.

Hi dont you ever have problems with too much sensitive dialing on hop up? I have flat hop installed on M4 and AK and in both of them I experience that they are extremely consistent but it is very hard to tune them because 1 mm move with hop up wheel makes huge change in BB path. Thank for your answer.

hello... I havent tried this mod but I was wondering if you can answer my question. I bought a replacement bucking for my AEG but after doing so my gun jams in full auto. it shoots fine in semi. I tried my cousins bucking and same result so we decided using the original one and it shoots fine again. Idk if there are differences between bucking colors but my original one was green and the new one i bought is gray and so is my cousins bucking. Id like to know whats going on with my hopup

can you just buy them already flat hopped>?

hey great video! Could you please post some more info on the rubber? I live in EU and we don't have those kinds of rubber and i don't know how much stiffness must it have. :D thanks!

Would this possibly work on a vsr 10 hop up too? I know with the stock hop up, the bb will shoot off to the right. And I was wondering if anyone knows much about that?

I have a couple of questions concerning this mod. Can i use something else instead of a Dremel to get the same results? And is dental floss really the best way to get the best seal? I'm thinking somekind of tape. Thx!

Even though then cutting a research is just buying a glat nub. You will have the same effect. Even better than five. Hopping would just be buying a maple leaf and they're calling it a day, but you will need the maple leaf nub. One thing I did notice is that it's a lot easier to do this on an AK slider chamber than it is a m4 rotary chamber and because of the way my stock chamber was designed, the arm would not come out. So I had to buy a ZCI chamber.

Hey man. are there feeding issues if you have your poppet dwell and rate of fire to high for the wolverine gen 2 inferno? Thanks

Still Great 🙌🏼

Why do you file the nub on the bucking?

How do I contact you to purchase a r-hop and tighbore barrel combination? Thanks for all you do!

How does this modification compare to purchasing an aftermarket system such as an rhop?

Sugru for r hop?

does the nub need to be perfectly square/straight or can there be slight imperfections?

Will Green g&g Bucking work with modify nub? After ther sanding procedur of cours

I know i'm a bit late to the party, but what hop up unit is that? it looks nice af.

How ol d are you? What are your engineering qualifications?

Is this a flathop?

The design is perfectly sound for the FPS and BB weights it was designed around.

i am looking into doing this but i was wondering if you could leave the dip in the hopup arm and cut the eraser to fit into the groove?

Do you turn the bucking inside out again after you shave off the nub and line?

Hi ! I wonder I can ask a very noob question here , and hope you don mind I ask the question here I got a problem to install my prowin hopup unit , and the bucking that I use is Prometheus soft type , and after I have done everything and I do test before install it into my aeg , when I turn the ring to press the buffer rubber down and I see through from the back of the hopup unit found that the bucking is not in good shape mean the shape like one side more down then the other side , may I know what wrong is it ? sorry for the bad English , hope you know what I mean .wish can put the picture here :( tks for view .

Yay!

Do you do custom work for hire? I just bought a Krystal vector. I’d love to have this professionals done.

Am I the only one who thinks this guy needs to take a vacation and get a manicure? :) that thumb needs some love!

I have a stock ICS G33. It comes with a flat hop. The bbs seem to be hitting the ground at about 55-60 meters and I want them flying further and with more accuracy. What can I do?

Will the flat hop increase fps? because i am shooting 358 fps and the max in my country (belgium) is 360

Hey, im from italy... and i dont understand what de pink thing is... could u tell me that?

You never explained how big to make the nub compared to the hole in the hopup unit

Do they not make buckings flat that dont have to be trimmed?

7:50 did you dremel your nail?

just here to let everyone know that my house comes standard with dish soap. liked and subbd.

Does this still apply to new airsoft guns now?

nice mod...i just fabricate a concave solid hop nub....flaten the mund part without removing it a seal it using silicobe sealant which can be undone much better than teflon.

So what are all the materials that i can use to make the nub m’dude.

Absolute legend Thanks, A random dude from the year 2021

Would this work better than a namazu firefly and a prommy purple

I don't understand why there are not pre made flat hop and r hop up assemblies. Seems like you have to rig a lot of airsoft guns because they are poorly designed from the beginning.

May be better to use plumbers tape than dental floss.

The fact that your not filming some steps, has me utterly confused as to what you even did with your dremil

What eraser brand is good for the hop up nubs?

could one, maybe use heat shrink around the bucking instead of dental floss ? ps, nice tutorial, easy to understand. :)

From what I gathered, is R-hopping just flat hopping with a patch over the barrel Window?

can I try this to flat hop my krytac?

Well i opened up my gun and i dont have a hop up arm .-. Also my bucking broke ;(

you just touched the barrel??

After that $$$ spent on R&D, an angled knub is more accurate than the rounded one. baffling.

NO matter if the nub is round as in the conventional hop up or rectangular as in your custom nub - considering basic geometry and maths the contact point of a convex or straight surface to a sphere is always one point. You'd need to make concave nub to increase the contact surface - so in real the difference must be abysmal

I might just be retarded but my gun was shooting beams anyway but max hop was just coping with .28g so I gave this a go and idk about anyone else who has tried this but its made my accuracy worse lmao, the hop just never seems to sit right and also its preventing me from going fullauto

Man this is harder then a 2 if your cutting your nub from erasers .

“Your mound is poorly designed...” HA!