HW 55 internal weirdness...

[MDriskill]

what is a normal FPE / FPS for a HW55 . I have one i bought a year ago and it is a sweet shooter , lighter than i thought it would be .

The HW 55 shared the basic receiver with the original HW 50 sporter rifle (MUCH DIFF than today's "HW 50," which was originally the HW 99). The old 50 was around 700 FPS with light .177 pellets. The 55 was detuned to be closer to 600 FPS for target use, by means of a lighter spring, and as we have learned here (!), a special piston seal detail. But it can be pushed up back up around 700 FPS and remain quite pleasant.

HW 55 accessories back in the day included 2 different barrel sleeve weights, and another supplemental weight for the large void inside the stock fore end - check out this old ad (but don't look at the prices...they will make you cry!). The heavy sleeve plus stock weight bring the gun close to the ISSF "legal" 10m match rifle limit (5kg, IIRC).

 

[MDriskill]

Thank you Chuck - that is very useful info!

I initially thought the "good" seal in my first post was from JG Airguns, but upon further review I think it's another one that I picked up elsewhere. JGA currently lists an HW 55 seal, but I didn't see a photo to verify what it looks like.

 

[Chuck-in-Ohio]

I have never laid eyes on the JG replacement seal to see if it is closer to OEM with the filler piece.

The Chambers seal assembly uses a plastic washer instead of the OEM Weihrauch phenolic filler piece. You will know it if you see one, as the washer is bright green.
I went with the Chambers seal over the Knibbs because I was super paranoid about that metal washer and possibly scarring the face of the cylinder if the piston slammed, but looking back on it, the Knibbs seal would have been fine in all likelihood.

 

[Mycapt65]

So do I change out the synthetic back to leather on my 50? The Fella I bought this from did the convertion.

Only if you are unhappy with the performance. I've converted leather guns to synthetic before realizing the transfer port differences. They still shot well but were a little down on power because they lacked the dieseling power boost from the oiled seal.
I always prided myself in building tight sealing guns that don't diesel. My pride and ignorance backfired on me when I didn't realize leather guns incorporate dieseling into the design.

 

[Chuck-in-Ohio]

what is a normal FPE / FPS for a HW55 . I have one i bought a year ago and it is a sweet shooter , lighter than i thought it would be .

1967 ARH catalog says 600 FPS is standard

I assume the 640 W/ special spring would be the result of swapping in the HW50 mainspring.
Pic is from an ebay auction........