Sudden drop in fps
Took the Edgun R3M 25 cal to the range today for some chrony #s and the velocity had dropped from 926fps to 615fps using 25.4 jsb kings. First thing I checked was the hst. The spring was compressed quite tight to reach the speed it was shooting at before, 926fps. Any thoughts on what could cause such a sudden drop?
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Took the regulator out and upon disassembly, I found the oring on the shaft with the washers was split. Could this be the cause of the drop in the fps? I’ve haven’t put the gun back together waiting on what you guys think. Ernest I followed your suggestion and polished the shaft before reassembling the regulator.
Thanks gents for your input. I will try each and every one of your suggestions.
At time the washers leave a ring wear mark on the piston that prevent smooth motion of the washers over the piston. before I tuned this edy the fps was erratic even after the standard tune, so after more detailed inspections I seen the wear rings on the piston, on this videos it shows how to clean up the piston without removing a lot of metal. after the polishing and testing I found the FPS consistency that I was looking for. not all regulator will benefit with this tune but will eliminate that part of the equation –there’s so many factors that will affect the SD/ES
Ok then, my bad ! :smilen:
Reg’s piston to be correct.
In front of the wheel 😆
Rotor? Thats the reg piston.. Rotors go around and pistons move up and down..
Thankyou for educating me today 🙂
It’s inside the regulator and it holds the belleville washers.
Here is a photo.
I guess he is referring the the part from the regulator. The one which moves to stop the pressure flow.
May be a silly Q but where’s the ‘rotor’ on an Edgun!??
Syclone,
We had the same problem with a friends R3M .25 std.
Gun was shooting very consistently at 915fps and suddenly after an air refill the fps dropped at 6xx.
I changed the rotor’s o-rings along with the rest of the reg o-rings since it was out of the gun and problem fixed.
My guess is that you have a failed rotor o-ring.
George.
There is only a few things it can be. First and foremost check your chrony. I have made the mistake of tearing down a regulator when it was a low battery in my chrony. The valve could be broken, valve stem bent, washers need clean and re-lubed and the O rings need to be replaced. First start with the chrony, if it’s accurate please provide a shot string and we will be able do diagnose the problem.
The last time I shot the gun, it was shooting at 926 fps. I hadn’t used it for a couple of months. Stored it with a 200 bar charge. Today when I shot it over the chrony, it showed 615fps. Checked the hst as mentioned and discarded that as a possible cause.
Its very hard to give any advise with so little info from your end. Was it 6xx fps from shot 1 to shot 55 or its slowing climbing to 9xxfps.
Anyway, with the hst nice and tight…sound like the reg need to be rebuild i.e. clean and replace all orings.
Would be nice if you could provide a string shot from 200b to 130b.
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yip, that will do it 🙂