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SS-arm/SS-nub Tutorial

8299 Views 23 Replies 9 Participants Last post by  SiliconeSword
Here's a tutorial on a nub I think I invented.
It was inspired by the MASADA arm, and before any of you say I'm copying him and whatever, I asked him to make this thread and he's chill with it.

Step 1
Acquire an Action Army chamber or really any hop chamber, but you may have to figure things out yourself.

Step 2
Acquire aluminum tape and JB Weld Steel Stik epoxy putty.
I have tried at least 10 different materials, and this exact one is the only one that worked out well.

Step 3
Put 2 bands of aluminum tape on your hop arm in these exact places, just barely covering the spring hole, and about 2.5mm from the nub groove.
You want your arm to be tight enough that it doesn't wobble at all, but you want your spring to be able to push it back up so you can still remove hop without taking it apart.

Step 4
Lightly grease the green areas with some sort of grease.
I used TechT gun grease, but you could probably do exactly as well with some chapstick or something.

Step 5
Wrap a perfectly round rod with some sort of tape, but you need to put some Scotch tape on the outside.
You would be preferably using a Delrin or Teflon rod with the exact OD as the ID of your chamber, but tape and a rod work perfectly fine.

Insert it into the chamber where the bucking would go.
It should be as tight as possible, with no wrinkles or imperfections visible through the hop window.

Step 6
Slice a small section off of the epoxy putty and mix it until you can't see a single light or dark streak, then mash it carefully into the hop window, making sure to poke the putty into the corners leaving as few air pockets as possible.
Save a little ball of the putty.

Squish down the arm so that it is roughly level.
This will ensure that you can have zero hop and a ton of hop, instead of just one.

Pry out the arm after about 10 minutes, or until the little ball of putty is pretty hard but not completely.
Then once you have it pried out, trim the excess so it looks like this.
You want the actual arm to be exposed like so, and you want the entire thing to be tapered inwards so you have full control of your hop setting.

Let cure overnight, and add new aluminum tape if necessary.
The aluminum tape is even better than most TDCs as it doesn't require irreversible modification, and keeps the arm/nub more stable that most TDCs.
The only disadvantage is that you still have to adjust through your magwell, but once you adjust your hop it will stay put until your contact patch wears out.

I encourage you to try this for yourself as it's almost free, and you can make a shit ton of nubs if you grease everything, that way you can pop it off.
Another thing I recommend to do if you ever want to remove this nub is to soak it in acetone for a couple hours and it will come off with ease.
You'll have to make a new one though, it will probably be ruined.
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Nice work! If you are really into it, you can use a 6mm round file and give it a profile so it grips the BB with a greater area.
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That's not a bad idea, but I think that would only make a difference with R-hop, but I still may try it whenever I get more ammo.

Anyways, thx for the reply lol
Nice, how did it perform after doing this?

For accuracy must have been a nice improvement?
I've been using this since last summer and was just waiting for a phone with a decent camera, so I've definitely decided that it works well.

I would say that this is EXACTLY as good as the Masada arm which is regarded as the best nub/arm available.
The three advantages over the Masada arm are the arm being aluminum, you can still use the spring allowing you to make the arm more rigid by using spacers while still being able to reduce hop, and the nub is perfectly centered to whatever chamber you mould it from.

The actual nub didn't really boost accuracy too much over an Omega nub, but Omega nubs have bad quality control and rubber deforms and develops curving issues over time, if they don't already come with them.
But the nub is ridiculously cheap as the epoxy putty is like $4, and you can make dozens and dozens out of one tube, which certainly beats a $6+ Omega nub, $12+ expensive shipping Panthera nub, and the Masada arm (reasonable $12 but Shapeways has costly shipping).
I will whole heartedly recommend the Masada arm, but only if you're lazy or clumsy.

What did boost accuracy is the aluminum tape centering the arm, probably better than most TDCs, but a centered arm with zero wobble is only as good as your nub, allowing mine to work flawlessly as the nub moulding will make up for any imperfection.

Btw, this nub will work well with stock buckings, R-hop, W-hold style buckings, and of course Maple Leaf bucking, which was a surprise, but a good surprise.
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Agreed aluminium tape works great.

I forget the arm i bought that's currently in mine, was from Airlab and it's gold coloured.

I have a gunsmithy arm but haven't bothered to install it yet.

Have been racking my brain trying to remember the name of it, but it hardly needed shimming the tolerances on it are really good, but i did use a small amount of aluminium tape. :)
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If there's space for aluminum tape, the tolerances aren't great lol.

Would you mind posting a picture?
I've never seen it before even through I've searched their whole site, must be discontinued.
The two arms I know that are gold are for the stock VSR-10 chamber, the Dangerwerx and the FireFly one, both of which are expensive (FireFly is $98) and outclassed by the Maple Leaf arm.

If you can, would you mind doing this to a stock chamber?
I don't have one anymore, but I'd like to know if it does truly work in terms of ease of installation compared to the AA chamber.
Feels bad bringing up an older thread - but it's on topic I promise.

I've been trying this same mod - low key thought I was the only one who was trying it. I do like your method more than mine. I've been doing the exact same process but using hot glue instead of knead it, figured it set hard enough to not deform and when it's hot it's really easy to get into the chambers arm space.

Good mod and great guide SS!
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That's cool man, I hereby declare this thread NECRO FRIENDLY.

Yeah, I thought so too, I think I had the idea maybe last April and got around to it in August, so idk who did it first.
The JB Weld steel stik worked the best for me and would probably work great for you, but wouldn't hot glue be impossible to work with due to the chamber and hop arm sucking away the heat on contact?
I just dunked the whole chamber in boiled water to keep it hot enough to get enough time to manipulate it.

I'm gonna try your approach - harder nubs are the business. I only tried this because carving a nub from hard plastic takes so long! While the custom made approach works awesome - I wanted a quicker process. The harder product will work better than hot glue - over time the pressure from the arm caused the nub to misshape and made the hop up do crazy things.

I think I had a chat with Zero about it around the same time you were thinking/working on it. So I'll give you the idea first ;) You got it made and up on the forum before I did.

What results do you find in terms of consistency?
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Oh dang, that's a bit involved for me.

Yeah, I hate rubber nubs lol, they've never worked for me, and I don't see a point anyways as your bucking is already squishy and probably need a hard backing to keep it in shape, which seems to be the case.
I definitely couldn't be bothered to carve a nub or arm from the ground up as the nub holder is not at all centred so I'd have to test, carve, test, carve, test, and buy a new chamber after I wear out the screw ports.

I really like my 5th arm which I'm using right now, I can't really think of any improvements(first 3 were figuring stuff out, then I had to take my 4th off to do the tutorial).
I don't think that the JB putty will deform anytime soon, especially not before a bucking, and it's in a very dark place and a pretty clean place so it'll probably last forever.
You can of course carve, sand, grind, and whatever else on this epoxy putty as it's meant for all that, so you could adjust length, shape, curvature, and texture if you were so inclined.
Still, plain old concave with the exact curvature of the outside of a bucking seems to be the best I've tried, and best most have tried.

Also, feel free to use this nub moulding method in any hop chamber, as I don't have very many guns to test in but I'm sure it would be great for most, as long as the can be assembled enough to be stable in whatever timeframe your putty says.
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I made an SS-nub for my Airsoft Philosopher chamber.
The original nub is slightly loose in the chamber, which possibly is why I have had a terrible experience with the setup (among other possibilities) so maybe this will fix it.
What you see below isn't completed, but all that I have to do it mill or carefully file the top flat and to a similar height so i don't get over hop at the off position.
Another cool thing about the SS-nub is that they are really cheap to make, so you can file, sand, mill, carve, or mould all sorts of different shapes, angles, and surfaces into the nub to experiment without having to get a bunch of original nubs and ruin them.

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Made one of these for a prowin m4 chamber paired with a regular bucking in my SR-25. Used the exact same process as mentioned above - this is a great mod to get a very responsive and consistent hop up.

Gonna try an ak hop next - that's R-hopped DSG and should be humming with this mod.
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Awesome, I think you're the first person besides me to do this lol.

Now I need to find somebody with a stock VSR-10 or something with a similar chamber and have them make an SS-arm to see how it works for them.
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I may try this with one of my stock vsr-10s and see how it goes. Probably will not get to it for some time though.
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This is a brilliant line of thinking Mr. Sword...I like it!!!!
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This is a brilliant line of thinking Mr. Sword...I like it!!!!
Thx man, idk why Action Army didn't include a second screw like this in the box that wasn't made of a singular piece of steel.
All of my stuff that I make is because I'm either too broke to buy it, or it doesn't exist, so most of my stuff is pretty legit.
I may move on from the AA chamber one of these days though, as I'm tempted to make a rifle with realistic mag placement and a Delrin hop chamber that doesn't use buckings, just an O-ring or two.
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Yes, yes!!!! Definitely the right line of thinking.
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Alright, third gun I've put an SS-nub in, an SSX23.
I'll probably need a steel plate on top due to rigidity and I'll definitely need to file down the bottom so I only apply contact to where I want to apply contact, but this is a great way to save on a $15 and $20 shipping H-arm and get as good or better results due to better fitment.
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The MK23 nub works great and doesn't need any filing or anything to work well even with the huge surface, and it drastically improves accuracy, from me hitting a license plate 15/25 to 20/25 on average, and about 5m more effective range.
I also gained about 10-15 FPS, likely due to a small temperature change, me putting on the little metal ring on my 2021 Autobot, me lapping my barrel to .50 micron, or assembling my gun slightly differently, but the nub may have contributed by having better BB contact, or by squishing down the whole top of the bucking so it seals completely.

All in all, this could save you $35 or so depending on how far your closest Hadron retailer is, leaving you to try and drill 2 more screw holes in your TDC for an injection molded non wobbly 3 screw TDC.
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