Fx crown plenum

Hello. I made my fx crown continuum 25 cal. Power plenum 13-15 cm3 steel with an adjustable valve spring.Hammer 10 g. At 150 bar. max speed with JSB MK II 984 fps and with NSA 33.5 gr. 971 fps. So far, that's enough for me. If you go more than 155 bars, you need 12 g. hammer. I have now started testing the new JSB KnockOut 33.49 gr. 951fps. The results are very good. With these settings I get 50 shots.

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Hi Monaro,

I dont think that Rogvi will make them.

I had my Crown apart today installing the larger 6.3 mm valve seat and a stronger hammer spring.

I already tried to make a 3D drawing for a similar to Rogvi Plug.

I 3d printed it and it fit without problems. So now I have a drawing - Looking for some to make me one in steel.

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Plenum 2.1641141623.jpeg


If somebody could machine a handfull I think they would much needed.

I drilled my original plug out from ø12 to ø13 mm.

Togeher with the new Titanium ø6.3 mm valve, and a stronger hammer spring it gave me + 30 fps at 150 bar.

Now there is a lot more power if i raise the pressure to 160 bar, but I really would like to keep it at max 150 bar.

Now the Crown is shooting the JSB Knockouts .22 / 25,39 gr with 940 fps so not a major power increase .

I hope that the larger plenum plug will make it more on top of the job.

At least so I could keep the speed, while lowering the pressure a bit.

I have the 600 mm superlight superior standard barrel - and it is a laser with Knockout slugs out to 120 yards.

Further out it opens up the groups too much. So I hope the extra speed will keep them in tight groups - also further out.

Best regards from Denmark

Claus
 
Rogvi,

Do you make these plenums for other FX Crown owners.I think you are onto a good thing here with plenty of Crown owners putting their hands in their pockets willing to buy these off you.You have done an exceptional job if you dont mind me saying so.I cannot understand why FX or Huma hasn't started making them!
Have you made one for the mk2. I have a .25 600mm Crown mk2 and would love to shoot 33.4 nsa at 970.