Beuchat SR550 gun???

At the end all the pneumatics are exactly the same.
the Beuchat is similar to the Cressi, Mares or Seac.

If you already serviced one the beuchat will be a piece of cake.

Ivan

There are standard O-rings, but it is realy important that you use the right size and change the oil or keep the right amount of oil in the gun. Remember that the mixture of Oil and compressed air is the life of your gun seals.

Once that you identify the right sizes of the different O-rings you are done, they are absolutely inexpensive.


If you service your gun once a year, even if it has no leaks, it will last forever.

Ivan

You can put the motorcycle fork oil.
It is really light and lubricates perfectly.

Ivan

...Beuchat sounds like French origin product.
I am familiar with most Italian brands which are almost identical in trigger mechanisms pistons. etc.
Until recently i was hunting with Cressisubs and never walked in a serviceshop for repairs or maintenance
The problem with cressisub guns included those sold today is the steel made piston and partly the metal part of the shock absorber.
I had to repalace all these parts with a british origin industrial plastic named ACETAL.
To service a gun like this follow this order.
Step one... Completely empty your air chamber to zero bars pressure.
two...Place a proper socket wrench and try to unscrew the front part.
Due to salt built up around the threads you may encounter difficulties at this point...Please be patient and never exert excessive force.
I have severely damaged my new Syrrano doing so.
Three...Remove safety lock and triger pins. There are two. One of around 3mm dia that holds the trigger in place and a slender one which pushes the
trigger engaging/disengaging hook(inner gun).
This last one you will need a slender long pliers to pull away.
All this done correctly you may now completely unscrew the front end which contains the the piston stop with shock absorber.
Screw back around 4 threads and using a plastic mallet tap the gun at the front. This will cause the barrel to travel backwards by few cm.
Remove completely the front end unscrew counterclockwise..
Now you can see the piston.
Insert the conical end of the spearshaft to facilitate removal of piston.
Hold at this point firmly the large diameter external cylinder(usually 40mm)with one hand
and tap the gun with the plastic hammer at the grip to remove the barrel.
At this point you are able for visual check of all o-rings and seals except
those contained in the one way air valve at the rear of the barrel.
To access this one you must firmly secure the barrel...never on a vice. This must be done on a round grip attachment. A lathe collet for example because all these parts are alumunium.
Now it is easy to replace seals...Your attention here please now.
Those seals are sensitive in mineral oils.
Use synthetic low viscosity motor oil. 05/30 or lower.
These oils are expensive... or try to find the original manufacturer's oil.
In my place there are specialty rubber seal manufacturers.
They can deliver to your specs...Ask for VITON rubber seals Are green in colour and can withstand high temperature and pressure environments.
Can be used with aggressive-to-rubber oils.
After inspection of barrel it should retain a mirror like shining inner surface.
If scratches are visible you better replace or hone.
Now if you are done and new seals are in place follow the reverse sequence.
I can't tell you though the exact torque specs for tightening back the barrel.
In my case I would completely tighten and the turn counterclockwise by 45 degrees angle.
Now fill your pump by one third with oil. \This is the equivalent with my pump diameter and length to 20ml.
Screw in the pump in pumping position and start pumping...I hope i was of help yo you.

Cheers

Happy hunting...