[status quo]

Is it possible to extend the G3/SG1 stock?

There is a knob inside the stock that can be loosened, is that supposed to enable the extension?

 

[Ultimate Shield]

Nope. Not sure what you mean by a nob. Only thing I can think your talking about is the screw in the back of the buffer. Adding a heavy butt pad is about as long as an SG1 is going to get, which would make its overall length roughly an inch longer than a standard G3 stock.

 

[status quo]

There is that wheel/knob you can turn but it apparently does not do anything. I thought you loosened it to extend the stock.

 

[The_Great_308]

There is that wheel/knob you can turn but it apparently does not do anything. I thought you loosened it to extend the stock.

That is not the stock HK buttpad. That is an E&L HK stock extension for the HK91/93. You can adjust it by adding additional spacers see the link below.

E&L Manufacturing e.Store - HK Accessories

SG1 stocks originaly came with a standard HK buttpad or you could change to the HK 21 rubber buttpad which as already said makes the stock approximately 1 inch longer than a standard HK stock. The E&L extension can be made much longer than the original.

 

[status quo]

It is a standard G3/SG1 stock. You can add a cheek piece to it and control the height.
The only relevant item at the link is a Recoil Pad which I already have. It's barely enough due to the extensive eye relief of the scope.
Still not clear what the rotating wheel is for. You can rotate it clockwise and counter-clockwise with no apparent effect on anything.

 

[The_Great_308]

It is a standard G3/SG1 stock. You can add a cheek piece to it and control the height.
The only relevant item at the link is a Recoil Pad which I already have. It's barely enough due to the extensive eye relief of the scope.
Still not clear what the rotating wheel is for. You can rotate it clockwise and counter-clockwise with no apparent effect on anything.

The knob/wheel in your photo is part of the E&L HK Stock extension order# 500, not part of the original HK SG1 stock. There are additional spacers from E&L that will extend the E&L stock extension farther to give you additional eye relief. The description does not give the length but based on the photos it looks like if you used the full E&L extension the stock would be as long as the MSG90 stock or very close. I do not know what the knob is for because I do not have an E&L stock extension. I do have an SG1 stock and there is another one in the WTS section here, they do not have the knob shown in your photo.

SG1 stock in WTS section:
http://www.hkpro.com/forum/hk-parts...k93-hk33-build-parts-accessories-updated.html

G3SG1 World of HK:
G3SG1

E&L HK Stock extension #500: Adjustable Stock Extensions - Extends the stocks length to accommodate your personal requirements. Fits all HK91/G3 and HK-93/G33 firearms with plastic stocks.

HK-91, HK-93
Order# 500 $29.95

http://www.elmfg.com/pics/500.jpg

 

[status quo]

This is what it looks like with the extension. I don't think I want to go any longer as it will be too long to handle.
The adjustable cheek-piece is in the same location as the stock in the referenced WTS post. It's the same stock configured differently.