Got bored and decided to see what the inside of the ASP looked like. Its really nothing too crazy. It does have a well made, big ol 30mm, 403g piston that rides on a synthetic bearing though. The piston seal looks like it may be interchangeable with an HW80 seal which would be great news (UPDATE: It does with very slight modification. See below for details). I'll start running part numbers on the gas ram to look for appropriate replacements if and when they start to fail. Worse case scenario a simple metal adapter should do the trick.
Tear down is pretty straightforward:
1: Remove both safety buttons
2: Remove front stock screws and front trigger guard screw and then remove the stock.
3: Pull the lock washer from the front tab that the trigger disconnect attaches to and then slide the disconnect off of the cocking arm
4: Gun in a compressor and punch out the end cap through pin
5: Remove end cap (careful not shoot trigger adjustment knob and spring across room)
6: Remove gas ram
7: Remove the trigger assembly. The sear that catches the piston may snag on the main tube. Slide it forward and off or you will not be able to remove the trigger unit.
8: Back out pivot pin set screws. 1 screw in the front of each fork
9: Tap out the pivot pin. I THINK I went left to right here and I'm not really sure if that matters or not. It punched out with relative ease so if you are struggling, something isn't right. I will update this on reassembly.
10: Slide the barrel forward and lift the cocking arm and shoe through the cut out in the tube.
11: Remove the piston
As a final note a steel adapter to convert it to a coil spring would be easy enough to make if needed or wanted. I'll probably play around with this a bit soon.
SPECS (UPDATED AS WE GO)
Piston Outer Diameter: 30mm
Piston Inner Diameter: ~0.780"
Piston Weight (with seal): 403g
Piston Stroke: ~90mm
Transfer Port Diameter: ~3.4mm (falls between a 3.2mm and 3.6mm drill bit)
UPDATE 4/20 : I THINK I FOUND THE OE RAM. BARE WITH ME AS I FIGURE OUT THE DETAILS
PISTON SEAL:
The Vortek HW80 piston seal does work like a charm but the internal dimensions are a smidge off making the base sit proud of the piston. I am fortunate enough to have a lathe handy so I just sized it down a hair. Took a minute if that. I then installed it and found it to still be a hair oversized. The factory seal measured 1.178"/29.92mm and the Vortek seal was closer to 1.188"/30.17mm. Being as its a Vortek seal I am going to just put a tin through it and see if velocity rises as it sizes itself. Currently I'm only about 25fps slower than the factory seal which is no biggie. I'm betting it rises but if not I'll just size it down a hair. I will try to update this as I go as well.
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