RA-Tech WA AGM NPAS Kit review



The NPAS kit was supplied directly from RA-tech in Taiwan. Their customer service is pleasant and friendly. They had already noticed from my website (in my email signature) that I had an AGM M4 and advised me on what part I would need.


The item was wrapped up in the retail packaging, covered in bubble wrap and then put into a postal envelope. The packaging had taken a beating through the post but the parts were undamaged upon arrival.


The postage took just under 2 weeks from Taiwan via the airmail letter postage service. This service was a tracked service. I was only able to track it as it left Taiwan and then it took ages to update, when I check again it was being delivered. This is no fault of RA-tech.

1st Impressions:

The NPAS kit comes in a plastic bag inside a small plastic box, the items look very well machined and no sharp edges or burrs are visible. There does not seem to be any instructions with the kit which I think could be a problem for people with slow internet access as they won’t be able to view videos for fitment of this part.



Fitting was easy, I used the official video from RA-Tech (http://www.youtube.com/watch?v=rN0tgnUUDcA). I came into a small problem when changing the little valve over from the stock rifle to the NPAS, I found that using a small punch and hammer made the pin removal easy but fitting it to the NPAS was really tricky and can be a 2 hand job or a lot of patience. The only other real problem I had was my AGM piston had a snapped part on the back of it (which didn’t seem to affect the performance at all). The part the NPAS was replacing however snapped on the last shot (was weak plastic I presume).


My rifle was firing at 380fps before I fitted the NPAS kit, I was unable to check more than 1 shot because the back of the part the NPAS replaces sheared off and jammed the rifle up.

When I fitted the NPAS I re-checked the fps and it was reading

  • Shot 1 – 439fps
  • Shot 2 – 430fps
  • Shot 3 – 421fps

After a bit of adjustment I was able to get

  • Shot 1 – 359fps
  • Shot 2 – 384fps
  • Shot 3 – 350fps
  • Shot 4 – 359fps
  • Shot 5 – 365fps
  • Shot 6 – 349fps
  • Shot 7 – 349fps
  • Shot 8 – 350fps
  • Shot 9 – 346fps
  • Shot 10 – 353fps

Hi: 384fps

LO: 346fps

AV: 356fps

ES: 38fps

SD: 11fps

The temperature at time of firing was 10 degrees; this meant that a full magazine would only do about 20 rounds before empty. Also because I could not set the power level either it caused problems with consumption of the gas.

All results were using green gas with 0.20g bb. Checked on a competition Electronics Pro-Chrono digital (for details about the fps results see the review of the chrono).

I was unable to check the Minimum and Maximum reachable fps due to the poor production quality of the AGM showing its ugly face. I now need a complete new piston and possibly a bolt carrier as this piston has now broken the holding tab too (also the barrel/front section fell off again).

Before it broke I found adjusting the power such a breeze. The little adjustment tool fits perfectly down the nozzle and allows adjustment of the power with out stripping the bolt to pieces. You just remove the body pin, slide the bolt out, turn to the desired amount, slide the bolt back in and test fire.


This is an excellent item; I would recommend this to anyone. Maybe not a RA-tech one if you cant afford one but a NPAS Is very useful, The RA-tech NPAS is constructed to a very high standard.

One thing I would also recommend is picking up a pack of their red o-rings as I had to use the one that came with the stock rifle and its not going to be as good as an aftermarket one.

It got my rifle down from 380fps to 356 fps and enabled me to use it in the UK. It also gave my rifle more durability as it’s made of aluminium rather than cheap plastic as it is with the stock rifle.

Just wish I could say the same for the AGM build quality.



Ease of adjustability:

Value for money: