walther lgu - spring maybe goosed.

[seagate]

My lgu is struggling , I think the spring may be fatigued even though it's not done that much .

Checked the breach seal which appears good and the piston seal is ok.

Anybody got any thoughts or info on the subject.

[TonyL]

There have been threads on this very subject in the past and in Jim's excellent article recently in Airgun World.

The word on the street is that the transfer port diameter is too small, leading to excessive choking and the resulting piston bounce wearing the spring prematurely.

The port needs opening out a tad.

Can't remember the recommended diameter, but it'll be on those threads and in Jim's article.

[seagate]

The tp is 2.6mm ish in standard trim , a mate reamed mine out to 3.3 ish.

[TonyL]

Has it lost power SINCE the rebuild and TP diameter increase?

Could be one of the seals, then; certainly worth double-checking.

I think the spring on the Walthers is meant to be very good quality, so maybe not the first, automatic port of call, but anyone's allowed a duffer from time to time?

[seagate]

I guess it must be a couple of years old now , had the tp done within a couple of tins of pellets from new.

It's always been struggling from day one.

[Barryg]

My lgu is struggling , I think the spring may be fatigued even though it's not done that much .

Checked the breach seal which appears good and the piston seal is ok.

Anybody got any thoughts or info on the subject.

Are you getting consistent fps?
Also have you measured the cocking effort so you can compare it to the correct cocking effort.

[seagate]

It's always been consistent , in fact very consistent.

The cocking effort - it never crossed my mind to think about that, so I've never measured it.I'm a dunce.

[Barryg]

It's always been consistent , in fact very consistent.

The cocking effort - it never crossed my mind to think about that, so I've never measured it.I'm a dunce.

If you are getting consistent fps I would think it unlikely to be the seals
I have found measuring the cocking effort a fair indicator of the spring and general health of a springer

[seagate]

Sounds logical.
Thanks for your input gentlemen.

[Phil Russell]

I bought a s/h LGU that was running c. 10.6. I had reason to believe it had been back to Armex because of low power. TP was 2.6. I opened it out to 3.2mm and with a small preload washer it went to c. 11.5, if I remember right. I then left the rifle untouched for about 2 months (uncocked before you ask) and power had dropped to about 10.5. I had bought a new kit from Germany so fitted the new spring. Output immediately regained 11.5. Rechecked two months later ... still 11.5.
I came to the conclusion that there were some duff Walther springs around.
Cheers, Phil