Ataman Ataman AP-16, lost speed...flummoxed

[far_shot]

Takes 7 to 10 shots to get to full power. Sits for ten minutes and then 2 or 3 shots to get full power. Cleaned the regulator and replaced all the O-rings. I don't have the little cylindrical rubber seal in the end of the regulator piston. It IS indented with the seat it seals against. Could that be the problem? Parts are hard to find, but PA has a regulator piston. Go for that?

 

[marflow 777]

i was just reading your Nov 2020 thread as you chased your tail on a leak
i was going to say you need to talk to that guy but you are that guy and i know already you have been talking to yourself
that damn pistol is complicated to the point of being scary to work on
i offer no help but do wish you great luck
it does appear that the regulator is the problem, takes a long time to fill, cause unknown
the real problem is you might know more about these then anyone

 

[far_shot]

Really not that hard to replace the O-rings once you figure it out. Bleed it out by dry fire. Air cylinder spins out and also spins apart. Regulator body comes out with the 2 top and two bottom screws and the regulator body comes apart with the remaining two screws. I took it apart again and stoned down the seat imprint in the regulator piston rubber seal. Didn't get it all removed but it did improve it a little. Guess I'll have to get a piston for it and then see if i can make a new rubber seal for the old piston

 

[far_shot]

I think I have it figured out ( long story). Took it apart again and stoned the regulator piston seal. I could not get the indent completely removed. Put it back together and it improved a tiny bit. Got a new regulator piston from PA and IT DID NOT have the seal on the end of the piston. Cut a 3mm o ring to fit and stoned it as flat as I could. Assembled and ......fissst....wouldn't even push a pellet out the barrel. Took it COMPLETLY apart and thought maybe the hammer was hanging up. It was very slightly cruddy. Cleaned, oiled and assembled. No go. Dry fire to bleed the air and noticed it picked up on the noise level as the air pressure went down. Started adding air a bit at a time and at 120 bar, it started popping really good. As I increased the pressure, it started getting quiet. AH HAH! The higher air pressure forces the piston and its home made 0 ring seal tighter and tighter into the seat to the point of sealing it almost completely off. 0-ring material is simply too soft. I found a hard plastic drive rivet in my junk and will try to make that work. I'm betting it's too brittle and will fail in short order :-( If not, eBay has 3mm Delrin rods for $12.00 and China is the only vendor :-(
We will see.........../

Original piston seal. Damaged from picking it after it didn't work.


Drilled a hole in the seal to remove it with a screw. It was tight!


Plastic drive rivet. 3 mm shank.

 

[dv8eod]

Hope it works. Haven't had issues with mine, but I know the time is coming.

 

[far_shot]

Well the plastic seal didn't work......at all. Apparently too hard to make the seal. Fire a shot and it bleeds the air out the barrel like it does when you hit the low reg pressure limit. Possibly may be too short, but I never measured the OAL of the original one before I dressed it flat. Ordered Delrin 3mm diameter round stock and I'll go from there. Hope that fixes it as Ataman AP-16 parts are nearly nonexistence as near as I can tell

 

[far_shot]

Well CRAP. I received the 3mm Delrin rod and made a new seal for the end of the regulator piston. Aired up and it now holds air from leaking out the barrel but has no power. I've had it apart a dozen times changing regulator stack and shortening the piston seal (that I made too long on purpose). So in the end, I put on the cylinder with 150 bar and it shoots very well for about 3 or 4 shots and then bleeds out after it hits 100 bar (they do that). Aired it up to 250 bar and NO POWER. Jacked up the hammer spring pressure and hardly no difference. Took the air cylinder off and got 9 shots out of the air that remained in the plenum.1st through 6th were very weak and the 7th and 8th shot were feeling like full power..... and then it bleeds off on the 9th shot. I have three conclusions. Full cylinder bar pressure is bypassing through the regulator and the hammer spring is not enough to open the valve until the air cylinder gets down to about 150 bar.....or the spring stack on the piston is set too high, putting too much bar pressure in the plenum which the hammer cant overcome.....or the piston seal I made is leaking by to full BAR in the plenum instead of regulated pressure. Anyone know the correct spring stack? I took a picture when first pulled it out, but that doesn't show the correct stack as ((()()))( would look the same in the side view as ()))((()( . Info on the internet is pretty much a ghost! DRATS!

 

[far_shot]

Looks like I am here all alone............nobody cares to learn something that may be your own issue some day?
So I had this crazy idea that the brass seat for the regulator piston to seal against... surely must have an O-ring to seal it in the aluminum body....and it could be leaking full pressure past the regulator. I was correct and it was leaking for sure after I got it apart... but what a damned dealio to get it apart. Description with each picture


Regulator piston seals against this brass seat. How to get it out ?? Cant just poke a needle nose pliers in there and risk wrecking the seat and end up with a $1,000.00 paper weight :-(



Made a tool and sacrificed a drill bit for the driver pins.



0-ring was toast. Hard as plastic and broke when I picked it. THAT was the problem all along :-(




Threaded brass seat and its hardened 0-ring.



Reassembled and ...it's working, not great but its working decently. Regulator creeps after sitting a while so it may be the piston seal I made out of Delrin or the regulator is still settling. Not sure what I had for FPS when it was working good...cant remember but this seems a little slow. May have to rearrange the washer stack "again" or crank up the hammer spring pressure. I can take this silly pistol apart in less than 5 minutes after having it apart a dozen times the last few days. Probably over 10 hours in fooling around with it My Dad would have said " You're going to wear it out taking it apart"


6 quick shots in the wind at 55 yards It has done way better than that on a calm day. Cheap Wal*Nards Crossman pellets

 

[dv8eod]

It's not that nobody cares; quite the contrary, but so far you are the only one known that has dug this far into it and no one else knows what they might be able to add that you haven't discovered yet. Couple that with the fact that not many people have one to begin with since a few were sold off when parts dried up, and those of us who don't get a chance to shoot but maybe two weeks out of the year, such as myself. Interest in what you have done will be lacking until Murphy jumps in.
Don't feel like you are hanging out in the wind. I for one really appreciate the time and work you have put in. Honestly speaking, it's worth alot more than 75% of most of the other posts I've seen lately.

 

[Airgun-hobbyist]

You've been deeper into these than most of the owners. Maybe give Pyramid Air a call. They used to be the custom shop with them so they had them apart a lot.