NPAS Question

[jond36]

As we all know the NPAS bolt can increase or decrease FPS on a M4 GBB or a SCAR GBBR or what have you. Does increasing your bolt to say 450-500+ FPS have an effect on the magazine.

 

For example, If I have a G&P M4 and increase my bolt to 475 FPS. Will I be able to finish the mag? or will it guzzle so much gas or have such a cool down it wouldn't be able to finish.

 

Same with a 300 FPS. Will I be able to have a much smoother full magzine of gas to fire?

[UrPeaceKeeper]

As we all know the NPAS bolt can increase or decrease FPS on a M4 GBB or a SCAR GBBR or what have you. Does increasing your bolt to say 450-500+ FPS have an effect on the magazine.

 

For example, If I have a G&P M4 and increase my bolt to 475 FPS. Will I be able to finish the mag? or will it guzzle so much gas or have such a cool down it wouldn't be able to finish.

 

Same with a 300 FPS. Will I be able to have a much smoother full magzine of gas to fire?

 

I believe the NPAS System works by the gas that would normally go to either recoil or FPS and directs it the other way, so for lesser FPS you'd have slightly more recoil for more FPS, slightly less recoil... gas consumption should remain the same as the only thing that affects that is the hammer and it's spring.

 

Then again, I'm making an assumption there.

[snorkelman]

Cant speak for the NPAS assemblies on the WE havent kept up with those On the WA NPAS a fully open npas shouldnt really give you any more power than a stock valve setup - cos fully open the npas flute valve should be sat at same position as a stock flute valve. You might be able to get it to sit a teeeeny bit lower but you'ld be looking at gaining a few fps tops

 

 

the npas will not affect the recoil phase of the stroke, as the WA doesnt use a fixed charge of gas, instead once the flute valve closes off the nozzle gas will flow to the blowback chamber until sufficient has hit the blowback chamber to see the bolt recoil approx 12 to 15mm - at which point the valve lock is depressed by the bolt carier and disengages from the valve allowing the mag valve to shut off flow.

 

cos of that the only part of the gas consumption the npas will have any real impact on is the amount fed down the nozzle prior to the flute valve closing. Set the power low it'll eat less gas on that phase of the stroke

 

..on a standard 14" barrel setup at 20 degrees c using green/propane around 2/3s of the gas consumption is blowback phase.

 

So any savings you make would be solely within the 1/3rd or so of the gas consumption that takes place in the firing phase.

 

Set the npas so that the guns kicking out around 300 to 320 fps and at best you'ld be reducing that particular 3rd by around a 3rd - which a 9th of overall consumption. Likewise if you did manage to get a teeny bit more fps out of an NPAS over a standard valve (say 480 versus 450) then the worst case scenario might be in region of an additional overall consumption of 5%

[Warpix]

Having a RA Tech NPAS running in my AGM (Yes I feel a little silly for spending more on the bolt than the gun), I noticed that I was able to finish a full GHK mag on full auto at 500fps and still engage the bolt catch. I'm not sure if it takes more gas this way, but I can say that you should be able to finish off your mag running at a higher fps.

[jond36]

Thank you for your help. I am thinking of using a G&P M4a1 as a Systema type weapon. As in using two seperate bolts one normal (450-500+ FPS) and one for CQB (328 FPS).

 

I am just trying to think of whether or not i want to invest in a second NPAS for a long range bolt.

[Warpix]

I would recommend getting a RA Tech NPAS since you can adjust the fps easily(300fps-500fps), but hey, its your call.

[greg]

I am just trying to think of whether or not i want to invest in a second NPAS for a long range bolt.

As UR describes the npas does not control or effect how much gas is released & therefore does not 'use' more gas than a non-npas system.

 

The n-pa simply controls the split of the gas between propelling the bb & operating the blow back. It just changes the split ratio, allowing you to change how quickly the gas nozzle is closed, after the gas is released.

 

This will not effect the operation of the gun, only the fps.

 

Be aware that in most cases, it does not increase the fps by much, on the maximum setting. Maybe 20 fps, but it does allow you to turn it right down.

 

Consider it a control aid, not a power booster.

 

 

Greg.

[cpldave]

Just thought I would chime in and mention that some places do provide ppas sets (positive pressure adjustment systems), which are a way of putting more gas down the barrel and up'ing the FPS. I've not got a GBB rifle, so I'm not much of an authority on either systems, just thought I would mentioned having seen a ppas system kicking around.

[jond36]

Consider it a control aid, not a power booster.

 

That's what I was looking for. Thank you.