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Fattened Barrel to Fit AA Chamber: Eliminate Unnecessary Part, Increase Cohesion

4K views 20 replies 5 participants last post by  Jeppe 
#1 · (Edited)
It's nothing huge, and I know my barrel isn't the first to employ this general idea, but BMR mentioned not seeing this mod before I made a casual post about it in the Facebook group.

So here's what I'm talking about:


I asked- scratch that, I sent ghetto MS Paint pictures of what I wanted to Ed (EdGI) depicting a barrel of standard shape, with the addition of a fattened section to fill out the AA chamber (replacing the black metal piece it comes with), along with a notch running the circumference which would line up with the AA chamber-secure screws to give extra grip. Ed took my design and improved it by making my notch into what is essentially a thread-less roll-able screw hole that perfectly fits the screws with virtually no wiggle room (I doubted such little wiggle would be possible, so I didn't even ask), and an O-ring (holy crap is it tight- I don't even really need the screws with that thing there).
The sleeve is friction fitted and bonded to the barrel.

He really knocked it out of the park. There is no barrel on Earth as secure to the chamber as mine :lmao:

My motivation for this mod was caused by two things:
  1. Honestly every barrel I've ever dealt with has been concerning-ly insecure, at least on the z-axis, and while the VSR/AA platform at least uses screws...
  2. I've had some REALLY BAD TIMES involving relying on x/y-axis pressure to ensure z-axis security- screwing things down too tightly because I'm paranoid and then STRIPPING THE TINY F#!&$R ... genuinely traumatic times

So yeah, there it is. A more secure solution barely involving screws. I don't even think he charged me extra..?
 
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#6 ·
Same principle as yours, pretty much the same design as well. With the exception being instead of an interference fit, it uses 2 tight fitting o-rings to hold the barrel.

The full design I had called for a total of 5 o-rings, 3 on the inside 2 on the outside. I have since dropped 2 of them, one in the inside and one on the outside. The one on the inside would be a pain to replace and install, and the outside is not needed and overkill.
 
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#4 ·
This is basicly what i want, but with the fat part extended all the way so there is no hopup bucking on. Then i cut the lips from a bucking and glue them on, and install a wide contact patch into the barrel without bucking.
This seperates the contact layer and the sealing bucking.
 
#10 ·
See attached picture.
That's basicly what i want.
It would seperate sealing section and backspin section.
It means they can be worked with seperately. Ie. if backspin setup is fine, it is easy to try different front buckings without changing the backspin setup.

And nozzle can hammer into the front bucking without disturbing the backspin material (though it still transfers movement to the innerbarrel).
 

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#11 ·
Really what we should have is a hopup chamber/innerbarrel made in one piece (or epoxied/press fit from two pieces to keep cost down), where the front unscrews to install a set of bucking lips / sealing o-ring, and then just make a cutout in the unit for a patch, with a pressure block on top. It's like, 3 parts.
 
#12 ·
The thing I'd worry about with separating the rubber components like this is would be air seal. Once you take into consideration sufficient air seal and how that coincides with the pressure application...I'm not sure there's much improvement to be made over the current system.

But yeah chamber and barrel might as well be one unit in some sense at least- too many platforms seem to just barely hold the two together.
 
#13 ·
The nozzle-front bucking will be able to me made incredibly well.
Where it could leak is through the patch window.
I silicone cast my patches with full seal, but obviously that's still a possible failure point. I have some tricks up my sleeve at that point, but given my experience so far with these patches, i'm not too worried.
 
#14 ·
Right, the backspin patch. Certainly not impossible, I could think of a few solutions...just not sure if it'd ever be worth it.
Do you mean you pour silicon to set in your window, sealed from the inside of the barrel? So you're saying the silicon has held to the metal quite successfully?
 
#15 ·
Yes. It binds very well, but it is not easy to apply correctly. There is also something with different adherence results based on what type of metal it is used with.

I have used it with my normal laylax barrel for 1 year now (since i cast that patch), with up to ASP M170 and steel BB. It still seals. Which tbh is beyond expectation.
That said, with normal use it is supported by the bucking and nub pressure.

I will experiment with different patch solutions once i get my hands on the barrel.
An idea is to have a curved metal piece sat halfway into the patch when it is cast, so the outside of the patch will just look like a raised bit of barrel. That will retain shape and support while minimizing wobble in the nub stack.

Or i could just loctite the patch into the window :p
 
#16 ·
Sounds interesting! I've wondered about this sort of thing. A long time ago I bought some bathroom tile sealer stuff for some project, and found that after setting, it held VERY well- even to smooth metals. Silicon should be great considering it makes up half the options from McMaster Carr tubing for in-window rubber :p
You should make a Youtube and document your endeavors!
 
#20 · (Edited)
Lol omg, looks so oddly huge, haha.
Seems like a concave Skeee nub would work great after simply casting the patch- very hard and well-fitted to the AA chamber (just picked them up, they seem awesome).

Keep us updated on that! Maybe just make a thread for your endeavors in attempting to separate the rubber functions of a hop-up unit..?
 
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