Airsoft Sniper Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
506 Posts
Discussion Starter · #1 ·
I haven't even finished with my VSR project yet, but I'm starting to think about another gun. ::) This would be a gas rifle... :)

So, could someone type up a fast paragraph about the differences between the pre-, and post-ban bolts. The fps has to go down to the 1J regulation, so is the air nozzle just tighter, and more restricted? Are there any other differences?
 

·
Registered
Joined
·
536 Posts
Here is what I know about it. Glad to be of assistance.

The PCS bolt, also referred to as "preban" bolt, features a Pressure Control System that enables the user to tighten or loose a "valve pin" into the rear of the nozzle. Inserting the PCS valve pin into the nozzle or moving it away modifies the amount of gas traveling from the magazine into the nozzle and through the nozzle onto the BB, pushing through the inner barrel. The more gas pushes the BB the more FPS, of course.

In the picture below (courtesy of Cerberus) you can see three Tanaka bolts.



(for the full sized picture, click here)

The bolt on top and the one in the middle are PCS (preban) models. The one on the bottom is a postban, NON-PCS model.

To get you acquainted with the different characteristics, I will point out the following hints you can get from the picture:

1. The bolt on top has the standard, stock nozzle (brass-colored)

2. The bolt in the middle has the King Arms (or Spartan Doctrine) Chamber Conversion Kit nozzle. Since these kits allows you to install VSR barrels, they change the hop unit and therefore the BB holder position and length. For this reason, the nozzle has to be longer in order to work correctly with the new chamber

3. The bolt on the botton has no nozzle installed

4. The bolt on the bottom has a G&G Rubber installed. The red round rubber you see is practically identical to the stock version (in black, present on the other two bolts). It is useful to replace since most of the time it is one of the pieces that wears out easier. That rubber gets into contact with the gas-exhaust valve on the magazine. A weak seal in this area is going to negatively affect the rifle power

5. The bolt on top and the on the middle have their PCS valve set to around 20%. You can see that metal threaded ring is the actual valve regulator. If you look across the black (or red) rubber valve you'll see what I called the "valve nail" that goes some way close to the beginning of the nozzle. The more that round threaded PCS wheel is turned to the RIGHT of the picture, the more the valve pin is going to go FAR from the nozzle, allowing more gas into the nozzle (= more fps)

6. Even with a fully open PCS (which you should not unscrew over 90% of its thread, because it might lead to leaks through the valve itself, because of a weaker air seal) your nozzle might still be restricted. A restricted nozzle has a distinctive inner ring in the inside.

Here is a picture a of a restricted nozzle (you can have a restricted nozzle even with a preban PCS valve, so it's worth checking!)



Here is my nozzle after some careful drilling, to remove the restrictor. This made my Tanaka M40A1 fully, truly preban.



Notice that the nozzle that come bundled in the King Arms or Spartan Doctrine conversions have NO restrictors built inside them.

Hope this helped!
 

·
Registered
Joined
·
536 Posts
Cheese Man said:
Yes, you can screw the nozzle without taking apart the bolt. There is a tiny grub screw in front of it that you loosen, then you can just move it with your thumb. That is why it has ridges.
True (fixing that in my post), thanks!

Glad to be of assistance!
 

·
Registered
Joined
·
536 Posts
awagg said:
However, can't you just change the fps by adjusting the air pressure on your external rig? Why bother with the pre-ban dial?
Yes you can. You need an external gas rig for that, of course, which is something you don't have by default on Tanaka rifles.
 

·
Administrator
Joined
·
6,201 Posts
Actually its better in terms of consistency to use external rig than the PCS, PCS it's a nice feature but it's useful if you play at different field with different limits. Though it's pain to retune the gun every time you adjust the PCS.

Wolf
 
1 - 14 of 14 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top