Anyone tried one of these?

[Biker_Bob]

OK, I'm going to contradict myself here.
I just bought a 177 HW45 and a genuine HW shoulder stock from a forum member.
It was inevitably missing it's extended front sight, so I threw an old double clamp scope mount in the milling machine and cut the top flat with a post sticking up as the front sight blade - works a treat.
Initially the results were as previous, pretty disappointing, but I spent a couple of hours experimenting with different holds and I've got it sussed.
Basically the gun just needs to be supported under the muzzle in an open left hand. The right hand needs to be "thumb up", not gripping the pistol grip at all, the three lower fingers just touching the grip frame at the front and then the index just touching the trigger.
With this hold and shooting Superdomes the HW45 is extremely accurate, cloverleaf groups on my 10yd indoor range.

[Antoni]

OK, I'm going to contradict myself here.
I just bought a 177 HW45 and a genuine HW shoulder stock from a forum member.
It was inevitably missing it's extended front sight, so I threw an old double clamp scope mount in the milling machine and cut the top flat with a post sticking up as the front sight blade - works a treat.
Initially the results were as previous, pretty disappointing, but I spent a couple of hours experimenting with different holds and I've got it sussed.
Basically the gun just needs to be supported under the muzzle in an open left hand. The right hand needs to be "thumb up", not gripping the pistol grip at all, the three lower fingers just touching the grip frame at the front and then the index just touching the trigger.
With this hold and shooting Superdomes the HW45 is extremely accurate, cloverleaf groups on my 10yd indoor range.

Not sure whether you are talking abt HW45 with or without a shoulder stock fitted.

I assumed you meant without stock. I don't shoot anything particularly well and so always interested in this kind of info. With my HW45 Blackstar in my right hand with my left hand's fingers cupping the fore-end, I found my open right thumb ended up resting on the inside of my left wrist. Not exactly what you suggested but close to it.

I found the groups resaonably good for my skill but TWO INCHES ABOVE my usual points of impact. I expect the group size would improve with that hold/grip given more practice.

For verification and without changing anything else, I went back to my usual fire-arms stance with the pistol in my left hand. A slightly better group and bang-on central of the target.

This just goes to show, find whatever grip and tightness of hold works in terms of group size, and is comfortable, then set your sights' adjustment to get the pellet nearest to the punkt.

Today's lesson for me: Hold and grip really matters, and must always be exactly the same.

[Biker_Bob]

That hold description was for the HW45 with stock.
To be clear the right thumb is sitting up the right hand side of the top slide (or what would be a slide if this was a 1911).

For off-hand shooting I use the standard 1911 combat hold. Push the front bottom section of the grip into the back of your 2nd knuckle joints on the lower three fingers. Hold the pistol between these fingers and the soft pad below where your thumb joins your palm. The thumb should be floating, not touching the gun at all.