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3D Airsmith
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Discussion Starter #1 (Edited)
I finaly gave in and deside to share one of my secret gun mods :cool:

Reason : To reduce the amount of air that is used by the gun to get the same velocity
Notice:
  • Be sure to read and understand these instructions be for attempting this on your gun
  • Picts are from my 98c and this Mod may not work with an A5
Tools/Supplies Needed
  • A Open ended or Cresent Wrench
  • A metal File
  • 3/32 Drill bit
  • Power drill
  • A #2 pencil (or any other # so long as it has an eraser)
  • The Alen Keys that came with the gun or matching Sizes
  • Clean Rag (Things are going to get dirty)
Instructions
  1. Deasemble your gun and remove the Power tube from the body. This can be done by removing these 2 screws.

    Also If you have a Cyclone feed or a RT Trigger your going to have to disconnect the air line feeds them befor the power tube can be removed.
  2. Now that you have your Powertube removed from the body your going to need to remove the Steal braid hose and be sure to also remove the Velocity screw as well.
  3. Next we use the pencil to push the Valve out of the Power tube. Be careful not to crack the power tube because the valve is held in place with loctight and too much force will damage the valve and the tube.
  4. The part that is going to be filed off has been shaded red in this pict but it is a little deeper then you should go. Also don;t file the back part were the o-ring is because it will not fit back in the power tube correctly
  5. Once your done filing the front of valve sould look like this
  6. Now drill 2 holes in the back of the valve about a 1/16 to 1/8 of an inch deep. This is to alow some more air back to help recock the gun. also don't drill too deep because you may cause your valve to leak.
  7. Now reinseart the valve into the power tube and reasemble your gun
  8. This was not that hard now was it.
Notes
  • You will find that your going to to be shooting very hot when you do this mod and the velocity screw might not be enough to get it down so you my have to invest in a Rear Velocity ajuster or a regulator.
Feel free to post any improvments, questions, or comments that you may have.
 

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sticky worthy...

thanks for sharing Mortisdeum, great writeup :tup

You wouldn't happen to have a pic of the rear holes for blow back?

It sounds like you found blowback to be a problem without these holes?

I wonder if adding a small grove to deepen the three existing groves would make any difference (vs milling one side)?

thank you,
manny
 

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3D Airsmith
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1,689 Posts
Discussion Starter #3
mr_manny said:
thanks for sharing Mortisdeum, great writeup :tup

You wouldn't happen to have a pic of the rear holes for blow back?

It sounds like you found blowback to be a problem without these holes?

I wonder if adding a small grove to deepen the three existing groves would make any difference (vs milling one side)?

thank you,
manny
I don't have a pict yet but I will take one soon.
Also I made a mistake in the write up it should be only 1 hole not 2

The blow back I am talking about is what drives the hammer back and recocks the gun

The main reason iI did not do the other 2 groves is, IF you mill the other 2 groves you run the risk of damaging the 2 screw holes that are used hold the power tube and the valve to the body
 

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Please correct me If I'm wrong, but here goes:

Removing material from your internal bolt, allows for additional air volume inside of the power tube.
As the internal valve opens, the increased volume causes your velocity to increase...

I believe this mod would make for a more efficient marker?
You would be able to run a lighter rear spring, which would cause your marker to use less air per shot.

One thing I have questions on is regarding the required blowback hole...hopefully a pic will help me in this area.
 

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I believe this mod would give you the following benefits, that simply upping the velocity would not:

more efficient at same velocity = Less air per shot

I'm not sure, but you could also receive the following as well:
Less likely to experience shootdown
more consistent?
less kick from lighter rear-spring
lighter trigger from lighter rear-spring
 

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3D Airsmith
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Discussion Starter #8
mr_manny said:
I believe this mod would give you the following benefits, that simply upping the velocity would not:

more efficient at same velocity = Less air per shot
That is exactly it
 

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what about the rear holes for the recocking of the bolt? where are they located? id like to know, im thinking of doing this with a titanium hammer and a set of springs and rear velocity adjustment if i can swing it.
 

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3D Airsmith
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Discussion Starter #10
what about the rear holes for the recocking of the bolt? where are they located? id like to know, im thinking of doing this with a titanium hammer and a set of springs and rear velocity adjustment if i can swing it.
Sorry for the delay

The location of the two holes are on the back of the CRX

Hold the valve so that the 2 mounting screws are on the right. and drill two holes across the diameter with the pin in the middle

( o . o )

They should be no bigger then 3/32" other wise you start will screw the valve up.
 

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3D Airsmith
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Discussion Starter #12
If you do this mod how hot exactly is hot, is there any cons to milling your valve?
I have seen 98s go from shooting about 280 jump to about 365.

As for cons it does void the warranty and if done incorrectly will ruin the valve. Also if any metal shaving get in the valve body they can and will ruin the seal.
 

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3D Airsmith
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Discussion Starter #14
btw, i live <10 miles from where you live. Is there another way of cranking down the fps without buying a regulator.
Yes install a lighter spring or cut the stock spring down a little. I would not recommend cutting the spring though
 
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