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Top-Down Hop up

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9
I had this problem with my hop up. I've been experimenting with extremely long hop up contact patches. My problem was traditional hop up systems applied pressure to the patches at an angle. This made for improper hop, or, rather, not fully used hop. It was almost impossible to apply flat, even pressure along the full length of the contact patch.

So I had an idea. If I could put a screw, or something similar through the top of the gun into my hop up chamber, I could give the hop up a more even contact surface. Simply by pushing the furthest part of the hop up down would help out; the rest of the chamber could hold the nub in place, and keep it centered well enough.




These are my hop ups, the top is a Prometheus chamber, the barrel is vanaras 6.03 509mm, the bucking is a Prometheus Hard, the nub is an M-nub backed with metal, and the hop up is an XR-hop.

The second hop up chamber is a Madbull Ulitmate with a Prometheus 6.03 550mm, Madbull Red, sorbo nub backed with thin plastic, and the contact patch is a long flat hop contact patch.

The solution was simpler in my mind that it actually was to make.

I started by drilling a hole through the top of my gun, straight down, over the hop up unit. The first hole was too close, and the second one was right on spot. You can see the Prometheus's pink arm through the holes, to get an idea of where the screw is centered over the hop up unit.


Once the hole was made, I JB welded a nub to the underside of the gun:


The screw I used I modified to be easier to turn with gloves from outside the gun. I removed the head of the screw and added a dial I found at Ace. It turned out to be perfect for this application.











These last few pictures show how it all comes together, and about how it all fits together. All in all, I'm quite pleased with how this came out. It was fairly simple to implement, and is remarkably effective for the longer contact patches.

It was really interesting to see it start to take effect. Because of the way I have the hop ups set up, I set it normally at first. Then, once I get the correct amount of hop, I start to apply hop with the screw until I notice the bbs starting to hop more. What's really interesting is, as I start to screw the screw in further, the range of the bbs begins to increase. I don't know what spring I had in my gun, nor do I know what it was chronoing at at that matter. Using Matrix .28s I was getting about 200-250ft of range during the initial hop up setting. Once I set the secondary part of the hop up, I was getting 300-350ft of range. I was very impressed, and it was really interesting to watch the range slowly stretch further and further, without adding any extra hop, as I screwed that screw in.

As for the name, I was discussing this with a sniper friend of mine, and it turns out Noobie did something like this a while back. So, the name is his, considering it's the exact same thing he did, just, this is in an aeg, and not a vsr-10. But, regardless, I figured I would share the mod, and show how I did it to my L85.
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Nice work! +1 for you. How was the accuracy effected? What FPS are you at with no hop and with various amounts of hop up added?
bobgengeskahn said:
Nice work! +1 for you. How was the accuracy effected? What FPS are you at with no hop and with various amounts of hop up added?
I didn't test the accuracy, but I had no troubles hitting people all the day long. Best I can say is I was still able to effectively engage people at 300ft with the .28s.

As for fps, no idea. If I have some time I'll pull it out to chrono the gun, and see how far the hop up brings down the fps.
I have been playing with longer windows. Put a 10mm window in my stock G36 barrel and on my twin hop I went to 2 x 14mm windows. How long did you end up going total? Just from the pics you're around 20mm?
So you're applying pressure to the hop arm, not from the cog, but from a screw ~20mm in front of the cog. And you're doing this to avoid the angled pressure the regular setup provides. But given that the hop arm still pivots at the same spot.. isn't it still applying the pressure at the same angle?

Or maybe I'm missing something.. :-/
Recoil said:
So you're applying pressure to the hop arm, not from the cog, but from a screw ~20mm in front of the cog. And you're doing this to avoid the angled pressure the regular setup provides. But given that the hop arm still pivots at the same spot.. isn't it still applying the pressure at the same angle?

Or maybe I'm missing something.. :-/
I *think* what he did was elongate the hop up window in the barrel and in addition to the normal hop up arm, added another block that is adjusted by the screw. That way he can adjust each independently of eachother.

Other people have done thinks like this here (Vindi, myself, others) but this is the first I've seen where someone has actually added another adjustment mechanism... for better or worse. Seems like its just adding variables, but if it works I can't knock it.


I'm pretty sure this is how the system he uses works, thats how I would do it at-least. Its very similar to the Tanaka and KJW 700-series hop-up just with an added hop-up arm and an extended patch. MS-Paint!
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MSPaint is awesome. That's almost exactly how I've done it. The only difference is my nub is one long piece, backed with a strong metal backing. Thus, it is rigid, flexing as little as possible (if at all) in the middle, between the two hop up arms.

As for adding extra variables, I don't feel like it adds many. The nub's spine is rigid, so it doesn't flex much, hopefully not at all. The screw is stiff, as is the normal hop arm, unlikely to move, and not likely to give against the pressure of the bb. I feel the system is solid enough to apply even, consistent hop. However, it could still use more testing.

The Madbull chamber has a 12mm long flat hop contact patch. The Prometheus chamber has a 20mm long contact patch, right to the tip of the bucking.
Have you got the patch hopped to a minimum BB weight or can you disable the hop-up completely?

Could you provide some pictures of the patch? Did you sand it down and how?

Is the nub on the actual arm similar to HS5s M-Nub or is it still a regular cylinder type? (http://hsarmory.webs.com/productsandservices.htm)

Questions Questions Questions!
Your questions are even worse when you consider that I have two hop ups in this thread, lol.

Peyote said:
Have you got the patch hopped to a minimum BB weight or can you disable the hop-up completely?
I can turn the hop all the way off on both hop up systems, so I could hop anything from a .12 to a .88. Though, properly hopping a .12 would be close to impossible...

Could you provide some pictures of the patch? Did you sand it down and how?
Which patch? You can see the XR-hop patch is simply a longer r-hop patch, and the long flat hop is simply that, a long smooth bucking is the patch.

Is the nub on the actual arm similar to HS5s M-Nub or is it still a regular cylinder type? (http://hsarmory.webs.com/productsandservices.htm)

Questions Questions Questions!
The XR-hop's nub is one of HS5's M-nubs, the other is sorbo padding and a bit of rubber tubing for a nub.

Any other questions?
It isn't, and hasn't been. It's part of a project from ASM that you can read about HERE.

For those that don't follow the link, it's about the possibility of 600ft shots. That's right, 200 yards. Possible or not, I don't know, but I just happened to be in the right place, at the right time, with a perfect candidate of a gun. Only thing stopping me now is picking up some metal bbs and possibly a more powerful spring.
Now I'm just confused, I was under the impression that the XR was the same as the ER.

Do you think you could take a picture of all of your hop-ups components apart like a blow out diagram?

Sorry for the confusion but I must of read something that made me cross-eyed.
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A guy on Airsoft Retreat called Noobie made something like this for the VSR 10. He called his a TDC (Top Down Center) hop up. It's an awesome system, his has custom hop up arms with a screw hole in it so the thumb screw will always be pushing down in the center. I am lucky enough to have gotten a hold of one of these hop units, and his awesome M-trigger.

Heres some pics of my VSR hop:




here's the link to Noobies TDC topic on ASR http://www.airsoftretreat.com/forums/index.php?topic=86871.0
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Sadly this is all old news to some of us at the cutting edge ::)

Firstly can I correct you all......

TDC stands for Top Dead Centre, cuz that is the point of contact for the adjuster!

Noobie did not invent this style of hop, and even says so himself.

I've been running a TDC + long hop in my EMR and my 350 fps VSR for a very long time now, and I even made 1 for my CA M24 about 6 years ago.

I've even been running a system similar to starfolders in my EMR for the last 8 months because of the same problems he encountered, only I use 2 M4 bolts side by side that are exactly the same length and marked up the same, so I can adjust them the same amount, so I know the nub is going down at the same flat rate..... The only thing I havent done is the extrrrreeeemly long nub, mine is only 10mm long.....

Pics of version 1....... Version 2 was similar with minor mods...... Version 3 is the current 1 under test, including the twin bolt system





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lol, I'm still behind. I'll catch up one day. I guess I'm happy that I'm at least running on my own two legs and not riding someone else's ideas anymore.
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