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So I have been wanting to attempt a modification to my GBB (Gas Blowback) pistol magazines to turn them into High-Flow valves, which in turn will theoretically increase the velocity of the gun to some degree.  I can't remember where I saw the mod because it was probably a year ago or more.  Everytime I remember that I want to try it, I usually not able to or don't have the time to sit down and do it, and whenever I have the time to do it, I forget.  Until today.  I finally remembered and thus decided to take the opportunity to investigate whether the mod works or not, and if so, how effective is it.

Here we go...

In this case, I'll be using a TSD Tactical M9X GBB Pistol.


Everything inside and out is stock.  No mods have been done to the gun prior to or after the hi-flow mod was performed.

I was using the Air Venturi .20g White BBs.


Here is a video of the M9X Chrono test using the stock gas valves and Air Venturi .20g BBs




First, take the gas valve out of your chosen magazine.

Here is what the stock gas valve looks like (unmodified).

We want it to look similar to this aftermarket Hi-Flow valve. Notice that it only has two thin outer posts, while the stock valve has four. 




Question: How in the WORLD are we going to remove those two extra posts to allow for more gas to get through? 

Answer: The Dremel 4000 BABY with a cutting wheel thingy!!!! Or just a tiny file will do. 

Progress Bar = 50% Complete (1 Post Removed)

Progess Bar Still ='s 50%.  This is just a slightly different angle of the same valve:
Side note: Does anyone know a good manicurist? 


Progress Bar = 100% Complete Modification

Side by Side Comparison: 
In case you are suffering from extreme density issues here's a hint -
Left=Stock, Right=Modified

Take a can of compressed air/duster gas and blow of the modified valve to get rid of the tiny brass shavings.  Then reinstall back into the magazine that it came from.  

Like so...


Here is the end result:

But first...a few notes:  the BBs were getting stuck inside the magazine, just as they got to the feed lips.  I am not sure whether it was the lips or the BBs causing the issue, but the fallout was some intermittent dry-firing that you will see in the videos where I take a shot or two without the chrono giving a reading. 


So not much to write home about, but there did appear to be a bit of a boost.

Here's a recap of the readings I got per the chrono, in feet per second (FPS).
335.9
316.2
314.5
308.6
306.6
295
294.1

Next Clip, post-gas refill
313.7
314.5
308.5
307.7
304
301.9

Only the oblivious would miss the declining values. This, I suppose, isn't too much of a surprise, considering my understanding of the way pressurized gas works. Actually, the very first shot I got on the chrono with a full magazine at approximately room temperature prior to recording was 348 FPS. However, I was never able to repeat such a reading and the highest I got was the 335.9.

So those are my findings.

It would appear that this mod does work in providing the pistol with a small, yet noticeable boost in power. I also have to wonder about the cool-down effect from the gas, as I continued to fire the gun. The magazine got colder as the shots progressed, as is typical of propane gas to do, which in turn will reduce velocity. These are layman terms. The scientific explanation is obviously much more involved, but I believe that is the gist of it. If you have a better explanation, please feel free to share it with the group. Sharing means caring.

The next step would be to acquire an aftermarket, manufactured high-flow valve and chrono the M9's performance with it installed for a comparison to see if one is better than the other. Maybe the aftermarket option will offer more consistent numbers. Maybe not. I don't know. But I'd like to find out. Maybe I'll look into this further. Maybe I won't. Time will tell.

There are a few other tricks I'd like to try as well to increase power. I'll see what I can do to gather the resources necessary and, of course, keep you posted on any relevant developments.

Airsoft.

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