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Discussion Starter · #1 · (Edited)
Hi,
I just got my first sniper Well MB03 and was following the tips on improving the air seal with Teflon tape and silicone grease.

Unmodified there appeared to have no compression whatsoever. It measured 470fps with 0.20g with no hop.

I added Teflon tape to the bucking, under the piston o ring and on the nozzle threads. Silicone grease on the o ring and smeared a bit inside the cylinder. Pushing the piston past the threads was a bit tight but as soon as it cleared them it slides inside the cylinder well enough.
With the nozzle back on and thumb over it the air seal seems improved. It now takes about 3 seconds for the piston to hit the nozzle with an audible air leak from thecylinder.

Not the 10 seconds I've seen in YouTube videos demonstrating the mods but better than before.

Cleaned the inner barrel with alcohol and put it back together.

Tested it on 0.20g and no hop. It now chronos between 426-429 with an occasional 423.

Is it normal for the fps to drop this far when improving the air seal? How bad/OK is the fps spread? Should I remove the Teflon tape from under the o ring?
 

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Putting Teflon under the O-ring and using thick grease will create too much friction, slowing down your piston.

I suggest that you get a variety of O-rings and see which you like best.
Also, use light silicone oil, TechT gunsav, Tamiya CeraGrease, or some light motor oil on your O-ring as it sometimes boosts FPS.
 

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Discussion Starter · #3 · (Edited)
Putting Teflon under the O-ring and using thick grease will create too much friction, slowing down your piston.

I suggest that you get a variety of O-rings and see which you like best.
Also, use light silicone oil, TechT gunsav, Tamiya CeraGrease, or some light motor oil on your O-ring as it sometimes boosts FPS.
Thanks!

Won't a larger o ring have the same effect on friction as the teflon tape under the existing o ring?

Would silicone spray work? I've got a spare can.
 

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Thanks!

Won't a larger o ring have the same effect on friction as the teflon tape under the existing o ring?

Would silicone spray work? I've got a spare can.
A correct size oring will always seal better than using Teflon tape to force a seal.

A perfect size oring seals against the piston and cylinder during movement/pressure but has just enough room to not cause too much friction.

Using plumbers tape forces the oring out against the cylinder and doesn't guarantee low friction movement and a good seal under actual usage/movement/pressure.

Also silicone spray varies on manufacturers, sometimes the propellent can cause o rings or plastic parts to deteriorate as they have other chemicals in.

Silicone oil can also cause other silicone objects to swell so not always a good idea.
 

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Discussion Starter · #6 ·
I removed the tape from under the o ring, replaced the o ring, wiped the silicone grease from the inside of the cylinder and from the piston and sprayed them with silicone spray.
Cylinder still doesn't maintain a seal but fps jumped to 502-505 on 0.2g.
Thanks for your help.
 

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Test where the air leak is.

To do this remove the inner & outer barrel, cock rifle and cover the piston head with a finger ( I find thumb is best).

Fire and listen for where the air is leaking from.

Could be piston or cylinder head.

If it's your piston than you can either
A) live with it until the parts wear out and need replacing
B) get an aftermarket 90" piston and trigger
C) buy a large multipack of O rings and try them until you find one that works.

Personally option A or B makes the most sense if the power output is fine since the stock piston and trigger will eventually wear. If you choose to leave the stock parts and wait for them to wear out just be aware it will likely die mid game and you will need a backup rifle or it's a day's playing fee wasted.

Stock plastic pistons and 45" triggers at 2.3J could last for awhile or for the next 6 shots that's the problem with them
 

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Discussion Starter · #8 ·
I tried listening but I don't know how to tell if the pistons or cylinder head is leaking. I did wrap teflon tape around the threads of the cylinder head so most likely it is the piston.

I've not had the chance to skirmish it yet so don't know how good or poor the accuracy is with the stock parts.

Once I get a chance to skirmish it in the next month I'll have to make a call if it is fun and useful in it's current form and if it is enjoyable over my AEGs and that will help decide if I start upgrading the other parts. Although based on many posts it seems that the upgrade starts at the barrel end with the chamber(action army), bucking and inner barrel.

How much effect on accuracy will the lack of seal on the cylinder have? Is it worth worrying about it at this early stage?

Any recommendations on what they might be called or where to get the multipack of o rings from. I can't recall seeing them in my local diy store. Presumably external diameters have to be around the 20mm range?
 

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Hi, my last build was a MB02, which is internally identical to yours. It's a cheap toy and premium quality can't be expected.
But it's good enough to be a nice base for a sniper without breaking the bank and buying parts which cost more than the complete rif :)

Here are my suggestions:
Orings from Well are horrible. Get some 22mm outer diameter, inner depends on the piston. Often teflon tape is needed.

Cylinder head is often very leaky => teflon tape.

Hop up tends to curve to the left or right. But you don't need a new unit, this can be fixed:
tdc is mandatory
hu arm is plastic and tends to twist. To make it stiffer just fill the slot in the arm with epoxy. Fill the notch with putty and you get a type b arm. Shim it and it's perfect.
The Barrel is bridged, so you can't use ML rubbers. Either you have to file off the bridge or use an R-hop or a pdi w-hold. I use the last option and can hop 0.4g bb without problems.



What to avoid:
Never change the spring. This will break the 45° system and lead to a new trigger unit, piston, cylinder, cylinder head... If you want more power, it's much smarter to buy an a10.

If the barrel is straight, don't expect any wonders of tuning barrels. In my opinion they have the worst price performance ratio of all tuning parts.
 

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Discussion Starter · #10 ·
I wish I read your post before I ordered the AA chamber and maple leaf bucking.

I don't mind replacing the chamber with the AA but I didn't think the inner barrel would not be compatible with the bucking. Will the existing barrel fit in the AA chamber do you think? If it does I'll order the pdi w-hold bucking or a decent budget 430mm vsr inner barrel.

Are there any reasonably priced with decent quality VSR barrels? I know zci seem like a good choice but they are aeg only I think.
 

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I'm not sure. Afaik the vsr barrel is compatible to the hu unit, but it is bridged and not compatible to the maple leaf. So I would suggest to file of the bridge.
This video has some details on filing the window:
I have a similar setup but without golf lead and with the standard barrel and the modified hu arm and get the same results. Grouping on 30m is less than 10cm, which is on par with other builds.
 
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