LGV - The AGW "Simple tune" doesn't work for me

[Vernal]

Sad to say I still haven't cracked this. I first tried re-sizing the Walther seal, and managed to get the lip diameter from 25.29 mm down to 25.05 mm (the Walther seal seems very hard, and I had to attack it quite savagely to remove enough material). This gave me a "steady" push fit, much easier than before, but still fairly firm, and the energy only went up to 8.2 ft/lbs, so I fitted a 25mm Weihrauch seal, which gave me an easy push fit as supplied, but with 38mm preload the energy still only went up to 8.9ft/lbs. It does shoot quite nicely at this, but I still don't understand why I am getting so much less energy than Mr Tyler, using, I think, identical parts.

[Shed tuner]

that size is your TP ?

[Vernal]

that size is your TP ?

Untouched at 2.6mm, presumably the same size as the subject of the article. It does look tiny. I am waiting for the follow up article in AGW which, I think, is going to give a recommendation on TP size.

[Shed tuner]

Untouched at 2.6mm, presumably the same size as the subject of the article. It does look tiny. I am waiting for the follow up article in AGW which, I think, is going to give a recommendation on TP size.

I'd go 2.9 if not 3.0

[Vernal]

Thank you, I might have a go at 2.9, the first irreversible step!

[Shed tuner]

Thank you, I might have a go at 2.9, the first irreversible step!

just wait for Jim's article, then you'll have more confidence

[pelletcaster]

your blue seal is probably a VAC 25 (vortek), as the Walther seals I've seen are all green..

As Shed tuner said.

[pelletcaster]

Hi Vernal,

I've been shooting one of the first LGV-CU sience 2013 and have no intention to sell this gun ever.
It's by far the most accurate and nice to shoot BB I handled so far.

Last spring I fettled a LGV-Challenger, took some pics and measures.
This "F"-version produced 6,1fpe with JSB Exact 4,52 / 8,44 gr.

I'm afraid you have the German 5,5fpe-piston inside.
This gives you a shortstroke of 18 mm as the potrusion of the piston stem over the skirt goes 58 mm while the full power 12fpe-piston stem shows just 40 mm.

TP at all LGV AFAIK is 3,2 mm / 25 mm length and I dont think yours is different and you may check it with some drill bit shafts.

A blue 25mm-piston seal in blue is most likely a VORTEK seal which are very hard and most of the time oversized.
Genuine WALTHER ones are green with the right size and a HW one should do quite fine.

After the tune and about 700 pellets through the gun showed the most accurate results with
JSB Exact 4,52 / 8,44 gr.
11,1 fpe / 769,3 fps
max dev. 3,5%
std dev. 5,0 fps



Here some pics.

This is the genuine WALTHER 12fpe-tuning kit and the tuning trigger blade (with the two stage 1 & 2 set grub screws in).
I bought from here:
https://www.versandhaus-schneider.de...ducts_id/25698
https://www.versandhaus-schneider.de...ducts_id/27673

https://picload.org/view/dlrarall/20...j-kit.jpg.html

Go through the album - lot of information.


Good luck and keep posting.

ATB
Andy

[Benelli B76]

Had a brand new .22 one in from the RFD with the same problem. Opened the transfer port and it was cured immediately. I can't remember the drill size, could have been as much as 3.7mm which I use on a lot of rifles.

Baz

[BTDT]

just wait for Jim's article, then you'll have more confidence

I know for a fact that increasing transfer port diameter will increase energy efficiency, Jon, but in this case, there's a fundamental issue that needs sorting first.

I have my own LGV back after three weeks, during which it's seen plenty of indoor range use, and been used (not by me) to win the springer class at two HFT club shoots, so I can now try to figure out what could be causing the OPs very low muzzle energy.

[hmangphilly]

std seals are very tight

[pelletcaster]

Had a brand new .22 one in from the RFD with the same problem. Opened the transfer port and it was cured immediately. I can't remember the drill size, could have been as much as 3.7mm which I use on a lot of rifles.

Baz

Are you sure you're talking about the break barrel LGV or is it the underlever LGU?

AFAIK
LGU compression tube with TP length of 6 mm:
5,5 fpe "F"-version: dia 2,6 mm
12 fpe full power version: dia 3,2 mm. You may go to 3,4 mm.
17 fpe FAC-version: dia 3,5 mm

[Shed tuner]

I know for a fact that increasing transfer port diameter will increase energy efficiency, Jon, but in this case, there's a fundamental issue that needs sorting first.

I have my own LGV back after three weeks, during which it's seen plenty of indoor range use, and been used (not by me) to win the springer class at two HFT club shoots, so I can now try to figure out what could be causing the OPs very low muzzle energy.

I agree, seems too low even with a somewhat constricted port...

Vernal - can you please measure your stroke ? as the seal had been changed, it's possible it might not be standard ?

[Benelli B76]

Are you sure you're talking about the break barrel LGV or is it the underlever LGU?

AFAIK
LGU compression tube with TP length of 6 mm:
5,5 fpe "F"-version: dia 2,6 mm
12 fpe full power version: dia 3,2 mm. You may go to 3,4 mm.
17 fpe FAC-version: dia 3,5 mm

Sorry, you are correct, the guys reminded me it was an LGU underlever.

Baz

[Vernal]

I agree, seems too low even with a somewhat constricted port...

Vernal - can you please measure your stroke ? as the seal had been changed, it's possible it might not be standard ?

I'm not sure i know exactly how you measure stoke? I know that the cocking stroke moves the piston back 93mm, so I assumed that is the amount by which it travels forward when released, but is there another way? I will take the piston out again later (now under 2 minutes to do this) and check the piston length.
Thank you to everyone who has contributed so far, it is all adding greatly to my understanding of the complexities of spring guns.