Relum 527 power

[capt hindsight]

The best rifle air rifle in the world could be running short of power!

I put it through the Chrony and its only producing around 6ft/lbs, when I last tested it having replaced the springs it was running at around 8.5ft/lbs.

So either it was dieseling and is settling down or somethings wrong (piston seal maybe). I suspect the latter as 6 ft/lbs does seem low and the fps variation is very high too.

Any thoughts?

and not thoughts like 'use it to prop open the gate or hammer in tent pegs etc

[Hsing-ee]

In order to get the best from your Hungarian sharp-shooter you will need to replace the springS with a single spring (usually suggested is the BSA Meteor spring I think) and some kind of spring guide, floating, or fixed at the back end. A top hat would be good too. The inner spring on Relums serves to make the system coil-bound and reduces power and efficiency in a characteristic mid-20th Century Communist way. You can then process to the front of the piston and replace the leather knacker with a Vortek seal affixed with a Vortek conversion thing. You may have to drill and tap in order to do this.

The last thing you will need to do is measure the transfer port length, diameter and calculate the volume. You will have done this already with the swept volume of the cylinder. Then ask on the BBS about whether you should open the port up, sleeve it down, cut a small venturi in it or give it a girl's name.

Good luck and I hope you have it on song again soon. If you used OEM springs I suggest spring failure as the cause of the attenuated foot-pounding.

[capt hindsight]

Thanks for the reply, I'll have a look inside it.

It always seemed more consistent than it is now, I want to leave it original though as I like the twin spring concept despite all its failings. Cant remember if I changed the piston seal but I definitely did the springs.

[Phil Russell]

With care it is possible to drift (thump) the piston washer retaining rivet out and still keep it in a usable state for the replacement washer. If this fails and you do not want to buy a new rivet system, you can use a screw and nut to hold the piston seal. Tapping the piston for the screw might be best but it is also possible to use a screw and nut and have the nut fitting inside the spring when it all goes back together. A meteor spring is often recommended, but I did try one from an early meteor once and it was not too good. Maybe the later meteors had a beefier spring.
Cheers, Phil