25 cal R3M with erratic fps
Recently the gun had a leak. I found it to be the small oring that allows air into the air reservoir. I replaced and lubed it. Now onto my present problem. While shooting it over the chrony the fps are very erratic. I filled to 200bar and the 1st shot read 1027fps, the next one read 827fps and so on. I proceeded to adjust the hammer spring to no avail. Could this be an indication the the regulator needs to rebuilt with new orings?
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I believe this to be my particular case. Will tear down the gun again replace all the orings anyway. Thanks for the tips.
You’re right…
Took some time for me to “accept” that little hole in the cylinder….
Spring washers work under normal pressure – atmospheric one. The regulator is vented to the atmosphere.
Thanks Shooter3 for the excellent information :thumb:
Just would like to be sure that this kind of lube is suitable for high pressure compressed air (I mean that it is safe to be used).
Pippo, the best lube for spring washers is something with zero starting friction. The majority of lubes does not have that property meaning that more force is needed to initiate the motion than to keep the things in motion. You need a lube for precise mechanisms. The consistency should be more oil-like than grease-like, not sticky, really light. I know that e.g. Feinwerkbau has this kind of lube in their offer. The thing which is placed on the spring washers at the factory is simply a joke.
Are you sure that full tank plays any role here? If a high pressure regulator oring leaks then the pressure will go to the spring washers and will be vented to the atmosphere. I think that low pressure oring may be damaged.
Be careful though with the “washer stack”, they have to stay in the very exact order.
Does anybody know which is the best lube for the said washer stack?
I know it must be very lightly applied but I don’t believe in this case silicon based oil/grease is the best.
Is the original lube on regulators belville washers (generally speaking) a known commercial product?
There is a very good chance the piston Oring is leaking then. What happens over time the Oring gets smashed because of the high pressure and the work it must do. I see this causing regulator creep all the time. A tell tail sign is if the gun shoots really fast after sitting for a while with a full tank.
1) fire a few dozen shots to see if it settles down.
2) If that does not work I would disassemble and check / replace the orings on the washer stack
3) When reassembling make sure he brass oring between the reg and receiver is properly seated.
Those are the obvious fixes. I am sure there will be other suggestions.
Will do… Thanks
Yes
I suggest trying the following;
1) fire a few dozen shots to see if it settles down.
2) If that does not work I would disassemble and check / replace the orings on the washer stack
3) When reassembling make sure he brass oring between the reg and receiver is properly seated.
Those are the obvious fixes. I am sure there will be other suggestions.
Is the speed higher when the gun is full of air (220 BAR)
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Brother..
I think if you check/replace all regulator orings…you might get some good results …
Or…if you post a full shot string would be great..
Pippo..
You can use all types of moly grease on the washers inside the regulator…slightly…. if the grease based on petroleum even.. because there is no pressure in that part of the regulator …. it is zero pressure…
Otherwise..of course…only silicone grease must be used for the high pressure parts..