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GBB FNX-45 Tactical


Starblade54

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A friend of mine has one of the FNX and I found that the muzzle energy is lower when the shot is fired from double action ( decocked ) than from single action ( cocked -> fire ) strange...

Umm correct me if Im wrong but thats normal, all pistols and revolvers have less fps if you fire it in double action mode.

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Umm correct me if Im wrong but thats normal, all pistols and revolvers have less fps if you fire it in double action mode.

 

One pistol I have used did. It was the old Maruzen P99 Movie Prop back when it had the metal plate in the way of the valve.

 

However the remaining 24 DA/SA guns I have owned don't (excluding the rubbish KWC Pythons) or if they did it wasn't so noticeable as to give a large enough drop in performance as described above.

 

To me it just sounds like a poor show and a $250 odd one at that.

 

'FireKnife'

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I have found most of my DA/SAs do shoot a little weaker in DA. The hammer is released sooner (less travel) in double action and doesn't hit the valve quite as hard. It's hardly noticeable but will usually produce a few FPS difference. I assume it's a bit more exaggerated with the FN?

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I have found most of my DA/SAs do shoot a little weaker in DA. The hammer is released sooner (less travel) in double action and doesn't hit the valve quite as hard. It's hardly noticeable but will usually produce a few FPS difference. I assume it's a bit more exaggerated with the FN?

This is essentially what's happening. From the videos of the FNX it looks like the hammer is released really early (like, only 3/4 cocked) in double-action which is almost certainly what's responsible for the low FPS problem.
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Well I think I have to add details of what I experienced. The gas I used on my friend's gun is V-Gas from VFC, which some people in local FB groups said having higher FPS caused by higher pressure compared to other "mainstream" gas ( to name a few, Puff Dino, Guarder, WE... ). Some even claim they could not open the valve with weakened hammer spring on their raceguns.

 

If that's true it could explain some of the causes.

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This is essentially what's happening. From the videos of the FNX it looks like the hammer is released really early (like, only 3/4 cocked) in double-action which is almost certainly what's responsible for the low FPS problem.

 

My PPK/S and P226s did the exact same and not an issue (at least not one that made me notice). On a DA the hammer never goes back to the same point as it does when in SA anyway but it still seems to work. To me this just sounds like a glaring design flaw on a gun that costs enough to not have such flaws.

 

'FireKnife'

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As long as the hammer is strong enough to actually push the button on the back of the mag the distance the hammer goes back should have no effect on the power output of the pistol.

 

With the typical design of airsoft gun the hammer pushes the valve striker forward that pushes the button on the back of the mag.

Once forward the valve striker locks into place, keeping the valve open.

There is a disconnector lever that is fitted to the frame of the pistol that has a protrusion that rides in a groove cut into the bottom of the slide.

As the slide goes backwards the groove feathers out to a flat surface which has the effect of pushing the disconnector down.

The disconnector disengages the valve striker and gas pressure in the mag closes the valve.

 

The only things that have an effect on the amount of gas that reaches the blow back mechanism are:

 

The design of the valve on the mag.

The efficiency of the gas route between mag and slide.

The length of time the button is held open.

 

The last one is effected by the blowback speed so a strong recoil spring slows the slide and causes the gun to use more gas.

 

None of those things should make the gun more powerful since there is a rocket valve in the front of the loading nozzle that closes under gas pressure and stops the gas going out of the barrel, redirecting it all to the blowback mechanism.

 

 

The only time hammer position would effect that is if the gun is light striking in DA mode.  That could make the valve striker go far enough forward to activate the button but not far enough to lock.

The mag would then "burp" a small amount of gas which would give a weak blowback and perhaps a weaker shot.

 

That all depends on the design of the rocket valve, on most of my guns a light strike would produce a burp that wasn't powerful enough to close the rocket valve so you'd get a fairly powerful (but a bit down) shot with no blowback and then another DA shot onto an empty chamber.

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I got to try one of these out a day ago. I wasn't impressed at all. Not that I ever liked the FNX to begin with, I think its kind of hideous, But even beyond looks it was pretty blah.

 

Blowback felt sluggish but in a weird way. Not like there was anything wrong, it just lacked the snappy kick that the M&P has. There were issues with suppressors as well. Firstly, the suppressor we tried attaching for some reason threaded on crooked. Im not sure if this was the gun or the suppressor., However it was noticeable misaligned with the outer barrel (This was checked with the barrel removed from the slide).

 

Secondly, the weight of the suppressor dragged the outer barrel downward inside the slide, and made thegun unable to cycle properly. It was rubbing.

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