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Inner Barrel Lock-Down


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5 replies to this topic

#1 vanevery

vanevery
  • Gender:Male

Posted 18 July 2013 - 08:29 AM

Inner Barrel Lock-Down



This application and illustrated example applies to m4/m16 model airsoft guns.
It is not limited to these gun models but will not work with every model of airsoft gun nor every Hop-up type.

Definition: Inner Barrel Lock Down.
- Securing the Inner Barrel in a way that ensures there is no movement of the Inner Barrel whatsoever as the gearbox cycles, the Air Nozzle feeds a round, and then seals with the Bucking.
Locking-down the Inner Barrel is often linked to Vibration Control. I look at these as two separate things, but each one contributes to the other.

Inner Barrel Lock-Down / Most Common Approach:
- There have been many approaches and DIY mods for locking down the Inner Barrel through the years.
There is no wrong way to do it, provided whatever your DIY approach is actually works.
As of now, possibly the most common general approach is the Three Point Approach.
A combination of:
1. Barrel shims that secure the inner barrel and outer barrel at the muzzle.
2. A locking ring to replace the brass ring that comes with most if not all Hop-up's
3. A set of O-ring spacers placed on the barrel and directly in front of the Hop-up unit.
This approach is credited to HS5 and his Hunterseeker Armory. He also sells this as a kit that you can buy from various vendors.


______________________________________________________________________

Hop-up Units:
(Click on Images for Larger View)

- There are basically two types of Hop-up units for m4/m16 Guns: Split Design and One Piece.
Split Design:
Attached File  0713132109b.jpg   160.54KB   9 downloads

The Split Design stems from the original AEG Hop-up design and is mostly associated with airsoft guns that have plastic(ABS) Receivers/Bodies. There are some companies that utilize the Split Hop-up design with their metal Receivers, but most use the One Piece Hop-up Unit design now and do so in both plastic and metal Receivers/Bodies.
- The Split Hop-up is designed so that when the Air Nozzle feeds a round drawn through the BB-Ramp(lower part) and then seals with the Bucking, it literally pushes the upper Hop-up unit( Chamber and Tube) forward. The forward spring attached to the front of the upper part of the Hop-up Unit is compressed and helps the Hop-up unit return quickly to rest position. This is also known as Free Float. The purpose of this design has mostly to do with a theory that this design ensures proper/controlled feeding of the bb from the magazine.

One Piece:
Attached File  0713132110.jpg   206.07KB   10 downloads

- The One Piece Hop-up unit design is all one piece, so the BB-ramp and upper Hop-up Chamber with Tube are all in one, so it does not free float. So in terms of inner barrel stabilization, when the magazine locks in, it locks into the BB-ramp of the One Piece Hop-up unit. This in turn helps lock the barrel down and keep it from moving.

_______________________________________________________________________

Inner Barrel Lock-Down / Target Hop-up Unit Location /Split Hop-up unit Design:

There is one area of the Three Point approach I find does not work well with airsoft guns that use a Split Hop-up design. That is the use of an O-ring or multiple O-rings as spacers/buffers to prevent the Hop-up unit form being pushed forward and Free Float. I have discovered a different approach to this specific area and will share it with you.

First I will write out out the the simplified steps and then below this will be the step by step tutorial.
1. Remove the Forward Spring from your Hop-up Unit.
2. Cut/ Shave off the Forward Spring Base Post.
3. File the area so it is nice and smooth.
4. Remove your Upper Receiver from your gun and locate the inside location where the Hop-up Unit seats.
5. Cut a Block Pencil Eraser into sections and cut one of the sections to fit the open/flat space inside the Upper Receiver where the Hop-up Unit seats. This piece of Eraser is a Drop-in piece that will fill the space where the Forward Spring was utilized. It is intended to be a wedge buffer that pushes the Hop-up Unit as close to the Air Nozzle as possible for better air seal and at the same time hold the Hop-up Unit in place securely so that it and the Inner Barrel do not move.
It will look like this inside your Upper Receiver:


______________________________________________________________

Tutorial:

Hop-up Unit:
(Click on Images for Larger View)

Tools and Materials:
- Cutting tool: Knife / Scissors / Razor Blade / Dremel Cutting Wheel, whatever.
- File: Metal Hand File / Dremel with Grinding Stone bit.
- Block Pencil Eraser.
Attached File  image__2_.jpg   137.82KB   5 downloadsAttached File  imageCAJ6IFJE.jpg   153.99KB   6 downloads


Step One:
Remove Your Inner barrel and Hop-up Unit.
Separate and remove the Hop-up Unit.
I suggest you dis-assemble the Hop-up unit, but you do not have to.
Attached File  0707131753.jpg   203.72KB   9 downloads


Step Two:
Remove the Forward Spring on the Hop-up Unit.
Attached File  1029122143.jpg   104.63KB   9 downloadsAttached File  0713132019.jpg   162.28KB   5 downloads


Step Three:
Take your Cutting Tool and cut down the Forward Spring Base Post as much as possible.
Attached File  1029122056.jpg   116.99KB   4 downloadsAttached File  0303130929a.jpg   232.97KB   6 downloads


I used a Dremel for my first time doing this Mod.
A cutting tool works much better for this step.
I recommend a Straight Razor/Naked Blade.

Step Four:
Use your Metal Hand File or Dremel with Grinding Stone bit and shave the rest of the Forward Spring Base Post until it is flush with the Hop-up Unit body. The finished product needs to have a nice and smooth surface.
Attached File  0713132021.jpg   181.98KB   5 downloads


Step 5:
Wash and dry the Hop-up unit thoroughly.
Attached File  0706131858.jpg   117.69KB   5 downloads



Continued.................................

Edited by vanevery, 24 August 2013 - 07:07 PM.

Chicks Dig the Long Shot

#2 vanevery

vanevery
  • Gender:Male

Posted 18 July 2013 - 08:31 AM

Upper Receiver:
(Click on Images for Larger View)


Step One:
Completely remove the Upper Receiver form the airsoft gun.
Attached File  0706131701a.jpg   208.62KB   5 downloads



Step Two:
Turn it upside down and locate the area that accommodates the Hop-up unit.
Attached File  0706131659a.jpg   135.6KB   4 downloads



You will see an open Flat-space that accommodates the Forward Spring of the Hop-up Unit.
Attached File  0303131021.jpg   151.29KB   12 downloads

Attached File  0706131649.jpg   197.99KB   13 downloads

Attached File  0303131015b.jpg   113.98KB   10 downloads



Now........
Block Pencil Eraser:
(Click on Images for Larger View)

Step One:
Use your Cutting Tool to cut the Block Pencil Eraser into sections.
Attached File  imageCAJ6IFJE.jpg   153.99KB   5 downloadsAttached File  0303131007.jpg   273.89KB   5 downloads



Step Two:
Cut a section of the Block Pencil Eraser so that it fits the open Flat-space in the Upper Receiver that accommodates the Hop-up Unit Forward Spring. I suggest using a pair of Needle Nose Pliers to place this piece in its place in the Upper Receiver.
Attached File  0303130954.jpg   292.51KB   4 downloadsAttached File  0303131028a.jpg   266.42KB   4 downloads


This cut-out from the Block Pencil Eraser will replace your Forward Spring. Its purpose is to push the Hop-up unit as close to the Air Nozzle as possible for the best possible Air Seal, and at the same time, hold the Hop-up Unit in a set position not allowing it to move(free float), thus locking down the Inner Barrel at the Hop-up Unit location.
When your Hop-up Unit is inserted in your Upper Receiver, it will look like this inside of it:
Attached File  0713131851.jpg   170.11KB   8 downloads



This will be trial and error.
You actually want to cut the length of it a bit long for the Pencil Eraser will compress when the Inner Barrel and Hop-up unit are inserted and the Upper Receiver is closed. This Mod is intended to be Drop-in. So, there is no need for bonding it to its placement in the Upper Receiver.
This is also Not intended to be bonded to the Hop-up Unit body.

***Note***
Just because the Upper Receiver can close does not always mean the Hop-up Unit is set in its proper position. If the Hop-up Unit is not set all the way forward, then the Air Nozzle will not seal with the Bucking and your bb's will not feed.
A good thing to do after you have finished this Mod and before you actually test fire the gun is this.
- Plug in your battery.
- Take your lower receiver and turn it upside down.
- Locate the BB-ramp.

- Watch and visually make certain that the Air Nozzle crosses completely over the BB-ramp channel and seals with the Bucking every time you pull the trigger. If it does not, your Section of Pencil Eraser that you cut out is not quite right and your bb's will not feed.


Continued......

Edited by vanevery, 24 August 2013 - 09:47 PM.

Chicks Dig the Long Shot

#3 vanevery

vanevery
  • Gender:Male

Posted 18 July 2013 - 08:52 AM

Mega Teflon Tape Mod:
I am adding this because it is something I do that relates to Inner Barrel Lock-Down and Vibration Control, so I may as well post it with this thread.

I do not use C-Clips.
- Do not do a good job locking the Inner Barrel in place with the Hop-up Unit.
- Often have QC issues so that when locked in, the Nub is not centered as it raises and lowers through the barrel window and then through Hop-up unit window.
- They will not lock in properly if an extended length of a Bucking extends into the C-Clip area.

Standard Teflon Tape Mod:
(Click on Picture for Larger View)
Attached File  0814121238.jpg   88.04KB   10 downloads

A simple application of Teflon Tape at the tail end of the bucking to help increase air seal by decreasing air leaks.
A few turns of wrapped tightly is the basic approach.

Mega Teflon Tape Mod:
Attached File  0717131908.jpg   275.67KB   8 downloads

A massive amount of Teflon Tape wrapped around the bucking beginning directly in front of the Inner Barrel Window and extending the entire length of the bucking and then continuing onto the Inner Barrel until it reaches the end of the Hop-up Unit.
The intent is to wrap the absolute thickest amount possible that will fit inside the Hop-up Unit and extend this thick application all the way to the end of the Hop-up Unit.
Attached File  0717131905.jpg   253.13KB   4 downloads

Attached File  0717131907.jpg   273.85KB   4 downloads

Attached File  0717131908.jpg   275.67KB   8 downloads

Attached File  0717131932.jpg   155.72KB   5 downloads

Attached File  0717131933.jpg   167.66KB   7 downloads

Attached File  0717131932a.jpg   176.81KB   8 downloads



What this does:
- Locks the inner Barrel and Hop-up Unit tightly together, in place of C-clips.
- Replaces the standard stock Brass Ring as a much more effective means of a secondary stabilizing system.
- Contributes to Inner Barrel Lock-Down.
- Contributes to Vibration control. This Mod simply absorbs a lot of vibration stemming from the Hop-up Unit as the Air Nozzle seals with the Bucking during each cycle of the Gearbox.

Also:
You can even extend this Mod by then wrapping Teflon Tape on the outside of the Hop-up Unit beginning at the base of the C-clip area, then onto the muzzle end of the Hop-up Unit, and then onto the Inner Barrel. I find this to add a bit more benefit to Barrel lock-Down and Vibration Control.
Attached File  0717131939a.jpg   242.45KB   6 downloads

Edited by vanevery, 24 August 2013 - 09:50 PM.

Chicks Dig the Long Shot

#4 hunterseeker5

hunterseeker5

Posted 18 July 2013 - 09:14 AM

Nice.

Just in case somebody says "why" I actually did up a short thread on the importance of inner barrel stabilization here:
http://forums.airsof...19339#msg119339



#5 vanevery

vanevery
  • Gender:Male

Posted 19 July 2013 - 05:14 PM

QUOTE (hunterseeker5 @ Jul 18 2013, 10:14 AM) <{POST_SNAPBACK}>
Nice.

Just in case somebody says "why" I actually did up a short thread on the importance of inner barrel stabilization here:
http://forums.airsof...19339#msg119339


Thanks, man.
Barrel Lock-down is indeed a difference maker.
Long range is where I find it the most noticeable.

Most of my guns have the Split-Hop-up design, so I had to figure something out regarding the Hop-up Unit location.
I initially was attempting this with Rubber Washers, but those take a while to cut and shape.
The Block Pencil Eraser is super fast and easy to cut and shape, and does the job quite well.
The trick is to cut a little longer than you need, for it will compress.
This creates a nice, tight fit and holds the Hop-up Unit firmly in place.

Chicks Dig the Long Shot

#6 vanevery

vanevery
  • Gender:Male

Posted 24 August 2013 - 06:05 PM

I edited my OP adding pictures from PhotoBucket to reinforce every uploaded image.
The reason for doing this was I realized that in some Forum Skins the uploaded pictures were displayed in link form only and not the images thermselves.
Chicks Dig the Long Shot




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