What is the purpose of the brass ring and the spring in front of the hop-up?

[Derei]

I want to know what is the role and purpose of the brass ring that goes in front of the hop-up chamber and the spring that sits on the inner barrel in front of it.

I tried to look online, but either my search queries weren't spot-on, or the question is too generic, because I didn't find an answer. 

 

[EDcase]

They help to seal the hop unit to the nozzle.

The ring is a spacer to ensure the hop and inner barrel are centred.

The spring puts pressure on the hop to push it towards the nozzle so it keeps a good seal.

 

Edited August 12, 2021 by EDcase

[Rogerborg]

The ring is a shim that goes between the inner barrel and the hop unit, to help secure and stabilise it.  Pop it over the barrel, slide it down, and press it firmly in so that it disappears inside the hop unit. Because inner barrels don't have consistent thicknesses, you may find that the stock ring isn't a perfect fit with an aftermarket barrel.

 

The spring pushes the hop unit back against the gearbox, helping to create a more consistent distance between the nozzle, feed tube, and the hop bucking lips.  Just fractions of a millimetre of front-to-back play in the hop unit can create low or inconsistent energy, or misfeeding issues.

 

That's one of the issues with airsoft toys, they require fine tolerances, but have fairly shoddy engineering. There can be a fair amount of shimming needed to get everything lined up just so.  Gearbox gears are the most obvious example, plus these hop unit issues, and I've even had to fit shims inside a couple of motors to reduce the amount of longitudinal play in the shaft.

[Derei]

Thank you for all answers... I understand now. It may actually be an issue with my hop-up assembly and the bucking in this case. Even on my stock (brass) barrel, with stock plastic hop-up chamber, everything seems a bit too loose.

I encountered some really odd firing. The bb goes straight and then when close to target it makes a random sharp turn. I can only assume this comes from the hop-up, as the bb is losing energy and the inconsistent spin is affecting its trajectory. Perhaos as @Rogerborgmentioned, the tolerances are crap and everything is misaligned.

Question: Is a metal hop-up chamber worth (Snow Wolf Electrical AUG), or I'd better just get another plastic one, that may be better built ?

[Adolf Hamster]

1 hour ago, Rogerborg said:

The ring is a shim that goes between the inner barrel and the hop unit, to help secure and stabilise it.  Pop it over the barrel, slide it down, and press it firmly in so that it disappears inside the hop unit. Because inner barrels don't have consistent thicknesses, you may find that the stock ring isn't a perfect fit with an aftermarket barrel.

 

The spring pushes the hop unit back against the gearbox, helping to create a more consistent distance between the nozzle, feed tube, and the hop bucking lips.  Just fractions of a millimetre of front-to-back play in the hop unit can create low or inconsistent energy, or misfeeding issues.

 

That's one of the issues with airsoft toys, they require fine tolerances, but have fairly shoddy engineering. There can be a fair amount of shimming needed to get everything lined up just so.  Gearbox gears are the most obvious example, plus these hop unit issues, and I've even had to fit shims inside a couple of motors to reduce the amount of longitudinal play in the shaft.

 

 

pretty much as above.

 

some aftermarket designs do things differently, modify brand barrels for example skip the brass ring and have it as a machined part of the barrel. likewise the likes of the combat union hop unit uses a collet style system that allows you to properly clamp a barrel in tight.

 

some different style of guns don't use springs, ak's for example tend to use either spacer blocks or have the hop unit bolted directly to the gearbox although you can sometimes bodge a spring in there, or some designs just attempt to have the hop unit sitting tight in the gun (with varying levels of success)

 

 

[Lozart]

16 minutes ago, Derei said:

I encountered some really odd firing. The bb goes straight and then when close to target it makes a random sharp turn. I can only assume this comes from the hop-up, as the bb is losing energy and the inconsistent spin is affecting its trajectory. Perhaos as @Rogerborgmentioned, the tolerances are crap and everything is misaligned.

Question: Is a metal hop-up chamber worth (Snow Wolf Electrical AUG), or I'd better just get another plastic one, that may be better built ?

 

A sharp turn up or to one side? If it's truly all over the show then it could just be either crappy ammo but as you say it could well be the inconsistency. Certainly sounds like it all fits like a dick in a shirt sleeve!

 

A better fitting hop is definitely a wise investment but it doesn't really matter what it's made of. If it fits, is stiff and consistent without the adjuster wandering in use then that's the one you want!

[Guest]

I read the title and couldn’t help but think or Arthur Weasly

 

”And what, exactly, is the purpose of a rubber duck” 🤣🤣

[Stratton Oakmont]

The ring symbolises your commitment to the hobby and the spring tames all the powerful recoil of the aeg which is why you don’t feel any.

Edited August 12, 2021 by Stratton Oakmont

[Rogerborg]

1 hour ago, Derei said:

Even on my stock (brass) barrel, with stock plastic hop-up chamber, everything seems a bit too loose.

 

As in, can the barrel be wiggled around independently of the hop unit?  Worse case you could put some tape around it to try and firm it up. This is a pretty common airsoft bodge, I've just run a strip of electrical tape along my DMR inner barrel to snug it up inside the outer.

 

 

1 hour ago, Derei said:

I encountered some really odd firing. The bb goes straight and then when close to target it makes a random sharp turn. I can only assume this comes from the hop-up, as the bb is losing energy and the inconsistent spin is affecting its trajectory. 

 

Mmm, the Magnus effect is super when you get everything lined up just so and the spin axis is perfectly vertical.

 

If it's consistently going off to one side or another that's generally down to barrel misalignment, or pressure on one side or another of the bucking.  Inconsistent could be a loose hop arm, although you'd need pretty small shims to address that and I'd look for other causes first.

 

 

1 hour ago, Derei said:

Question: Is a metal hop-up chamber worth (Snow Wolf Electrical AUG), or I'd better just get another plastic one, that may be better built ?

 

The first thing I'd do is to clean the barrel.  Many barrels come lightly oiled for shipping, it's always worth giving them a thorough clean out and then an occasional wipe through.

 

Then I'd replace the hop rubber with a Maple Leaf, either a Macaron, or a Mr Hop, of 60 or 50 degree hardness.

 

And I'd feed it 0.28g BBs, or whatever it will hop.

 

I have no idea what hop unit is in there (all bullpups are pure degeneracy) so I wouldn't like to give any bad advice there.

[Derei]

Barrel was cleaned with 99.9 Isopropyl alcohol. Same for the bucking. Then I put the bucking a bit in silicone oil, to make sure is not dry. 
BBs used: 0.25g G&G PSBP (5.95 +/-0.01mm as i says on the bag)

 

The sharp turns were happening rather randomly, not consistent in one direction. And slight hop-up adjustments would affect it in a considerable an unpredictable manner (eg, tightening it a bit would make it worse, but the tightening it again, would make it better...).

For the hop-up, I wrapped some PTFE tape around the end of the bucking (making sure I don't get near the barrel window) and both under and on top of the ring a little bit, to ensure a snug fit. Then I gently pushed the hop-up chamber over the bucking and it didn't move anymore.

Another thing I did was to add a bit of PTFE tape at the tip of the barrel,to make it fit better in the inner barrel. Of course there is still the issue of the inner barrel vibrating inside the outer... but this is something more difficult to deal with.

All in all, now after the proper fit of the bucking and hop chamber the random deviations reduced visibly. The grouping is still bad (20cm at 30m shooting distance). Further suggestions? (r-hop?)

[Lozart]

2 hours ago, Derei said:

 Then I put the bucking a bit in silicone oil, to make sure is not dry. 

 

[Derei]

@Lozartthat's how I read about maintaining rubber buckings. In the same post it was also mentioned that if bucking is made of silicone, then it should NOT be touched by silicone oil, but for rubber they said is needed, or it can crack. So... i just followed the indications.

If you happen to know a better maintenance procedure, I'd love to learn about it. Also, if you consider that what I did should not be done, I'd love to hear why.

[Lozart]

7 minutes ago, Derei said:

@Lozartthat's how I read about maintaining rubber buckings. In the same post it was also mentioned that if bucking is made of silicone, then it should NOT be touched by silicone oil, but for rubber they said is needed, or it can crack. So... i just followed the indications.

If you happen to know a better maintenance procedure, I'd love to learn about it. Also, if you consider that what I did should not be done, I'd love to hear why.

 

Hop rubbers will wear out from use before they crack through drying out. The only place you need to get any oil on is the OUTSIDE when you're putting it into the hop unit to help ease it in (if it's a bit tight).

The main issue is that getting silicone oil INSIDE the hop rubber will screw up it's ability to properly apply spin to the BB which can result in shots going all over the place.

 

Some folks maintain that you need to apply some silicone lube to your rubber to keep it supple, I'm not convinced. I've had airsoft guns since the original non-blowback TM Desert Eagle and the TM SPAS 12 were released back in the 90's and I can honestly say I've never needed to lube my hop rubber! Hop rubbers are a consumable item, they will wear and need replacing at some point, if a rubber is YEARS old and has sat doing nothing it may go stiff but at that point, throw it away and use a new one.

 

Give you hop rubber a bloody good clean out with water and detergent, dry it off and see if you still have the inconsistency issues. Better yet, replace it with one that hasn't been dunked in oil.

[Adolf Hamster]

Any time i've had silicone on a hop rubber it hasnt taken more than half a mag for it to bed back in.

 

However that said, a hop rubber is a wear item, and lozart has a point that if you ever keep one long enough for it to have issues then just replace it wether it's dozed from age or worn from use.

[Rogerborg]

16 hours ago, Lozart said:

Give you hop rubber a bloody good clean out with water and detergent, dry it off and see if you still have the inconsistency issues. Better yet, replace it with one that hasn't been dunked in oil.

 

That, really. Maple Leaf macarons really are very decent.

 

Although kudos for everything else, that's all the right stuff.