I put a little something together for those of you questioning the use of the airsoft quad-rails on the PS90.
I ordered the airsoft quad-rail from KHMountain in HongKong.
I paid a total of $32 and the part took 15 days to get to my door from the time of payment.
The part is all aluminum and great build quality. The only thing I don't like is the finish, its pretty cheap and scratches easily. I will most likely end up refinishing it.
These are the parts as they show up in the box. No directions. Some modifications will be required to make this fit the actual PS90.
These are the main parts that need to be modified.
The round piece needs to be opened up to be able to slide over the barrel. I used a 3/4" drill bit.
The blocks needed to be ground down a bit so that they slide all the way into the PS90 frame. I used a bench grinder.
This shows the parts modified. The screw hole on the quad-rail need to be dremeled out a bit for the holes to line up. The included washer still covers up the modified hole. You will also notice I trimmed the side rails. This does not need to be done but it makes for a little more space around the cocking handles.
This last one shows the quad-rail installed
The whole process was very simple and only took me one night with pretty basic tools and the quad-rail fits great.
Post here if you have any questions.