Walther LG400 12 FPE conversion: Updated results

[Sven]

See http://airgunaccuracy.wordpress.com/wal ... ld-target/ for more info.

I made some progress with my LG400 power mod. It is now on the LG300 MK2 16 Joule regulator (Dominator new type) and started shooting nice 10 shot groups at 55 yards:

[Jon]

Sven if you shot two groups similar to that I would believe the so called temp tests on your site.
Get it cold white over -6, scrape ice off lens and fire. We do shoot down that cold and as high as boiling.

Aluminium moves like it or not but your tests is only over a relative 4 degrees of which sure signs of zero shift with top picky with a very poor grouping circa 6/7 low. I can see the zero has moved higher to the left number 6 with a good three shot group. Other shots in lower picky along with temp rise to near on top picky inconclusive.
Velocity is ok.

The actions the same as the 18 year old LG200 renamed and revamped LG300 then LG400 with menial tweaks. Known issues of temp shift unless bedded in right and free floating, ask anyone.

The actions flex in three planes even when bridged like yours, to say I was shocked was an understatement. Normally people only know of underside of reg flat flexing, theres two others above it, one is twist even with bridging rail.
It don't matter how much stuff flexes as long as its repetitive after each shot, therefore action is good problem lies with stock, cylinder and the joint with your two o rings. Cylinders when tight may or may not flex in a different plane throughout its pressure range, best one for that is the thin AA tubes. Have also seen free floated actions where cylinder slackened 1/16 of turns has created moving zero shifts low and left t right, but that's beyond me and no logic.

Another way to check stock deformation is to get it cold with action and scope on and mount in something solid that wont move ie substantial mill. Eye up an impact pointor zero on to an object 20 yards will do and keep checking whilst temp rises. The alum will move but not necessarily up or down but left or right. Generally this would be ok ignoring the cylinder issue if rear fixing is loose with play, worth a try.
Worst case at least you can identify what parts move.

Hows it shoot by the way.

[AdminMASTER]

...seems like this might be the UK's first self done power mod. thanks to Sven's instructions...


http://www.shooting-the-breeze.com/foru ... hp?t=21262

by: airgunmad (UK)

" I have just finish converting my New LG400 to 12ft lbs following SVEN instructions. I bought a new LG300 16Joules Reg factory set at 88bar then made an adaptor to fit it to the LG400 body.
Initially I could not get the power above 557ft sec so I removed the reg and split it ; so I could adjust the regulator power. Not having manometer, I tightened the grub screw by 1/8 of a turn. The power is now set at 11.5 ft lbs with JSB 8.4 ; I had to back off the hammer spring slightly. I have to do some more testing but I did do a shot count on a 200bar fill It done 90 shots.

The hardest job was unscrewing and splitting the reg. By the way a lot of people ridicule this rifle because of a problem loading the pellets this totally untrue "

[Jon]

Really easy like that doing it right is another thing.
The first LG300 were like that and all slung back or modded.