Huben .25 GK1 V3

[airgunmike56]

I got this end part at a good price from a AGN member, Works great on my 22 caliber pistol, I have it set at about 800 FPS with JTS 18gr pellets , but did see 1100 FPS 14 gr Crossman pellets while turning the power adjuster a little to much..
Mike

 

[MXBS]

Great job!

 

[MrP]

I just designed this insert for a 1 inch aluminum can I got (made by rockr1 at GTA) that is just small enough to not obstruct the iron sights. Designed with .25 cal in mind and is based on a design and old patent that Subscriber shared here that uses torroidal vortices to slow air flow. It prints as 10 separate baffles that stack in the can. It was pretty simple to design using tinkercad. The length of the stack is 6 cm, each baffle being 0.6cm thick. This attenuates sound better than an empty can, and better than a felt wrapped core that I had tried earlier.

I’m going to make some additional iterations with different spacing and adjustments to the leading edge of the forcing cone that pushes air to the outside

 

[weevil]

I just designed this insert for a 1 inch aluminum can I got (made by rockr1 at GTA) that is just small enough to not obstruct the iron sights. Designed with .25 cal in mind and is based on a design and old patent that Subscriber shared here that uses torroidal vortices to slow air flow. It prints as 10 separate baffles that stack in the can. It was pretty simple to design using tinkercad. The length of the stack is 6 cm, each baffle being 0.6cm thick. This attenuates sound better than an empty can, and better than a felt wrapped core that I had tried earlier.

I’m going to make some additional iterations with different spacing and adjustments to the leading edge of the forcing cone that pushes air to the outside



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Nice job MrP! I hope your one-off pays off!

 

[IMADMAN]

I just designed this insert for a 1 inch aluminum can I got (made by rockr1 at GTA) that is just small enough to not obstruct the iron sights. Designed with .25 cal in mind and is based on a design and old patent that Subscriber shared here that uses torroidal vortices to slow air flow. It prints as 10 separate baffles that stack in the can. It was pretty simple to design using tinkercad. The length of the stack is 6 cm, each baffle being 0.6cm thick. This attenuates sound better than an empty can, and better than a felt wrapped core that I had tried earlier.

I’m going to make some additional iterations with different spacing and adjustments to the leading edge of the forcing cone that pushes air to the outside



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Very cool! I’d be interested in some decibel readings if you do any. What’s the overall length of the moderator?

 

[MrP]

the length of the can in the pic is about 4.5” with the end caps. I have 4 other tubes of different lengths, I will try some shorter and longer stacks as well.

I don’t have any objective information on sound reduction - for my purposes “quieter” is good enough. It makes the shots sound like more of a metallic impact and less of a pop. There’s always that one dry fire at the end of the magazine - that still comes out as a sharp report type sound, but a bit less sharp and reduced loudness .


I do have a device that could to make/record consistent sound measurements but my other hobbies are taking up too much of my time. Some future project, perhaps

 

[MrP]

Am I correct that the barrel is tensioned on the GK one? I’m looking at the diagram and as far as I can tell the shroud is screwed onto the threaded end of the barrel, and when that nut at the very end is tightened, it tensions the barrel and pushes the shroud against the receiver.

If I ever am at the point of looking for something to fill my time, I might try to design and print an active/sealed shroud. I think it could hold up fine with good thread orientation, especially with the compression from anchoring it to the barrel / receiver. This would also require venting in the nut that attaches it to the barrel - it should be possible to 3-D print a very durable solution, or use one of those screw-in metal threaded inserts or some other solution that screws on the end (I can imagine building something around a hatsan airstripper, for example)

 

[weevil]

Am I correct that the barrel is tensioned on the GK one? I’m looking at the diagram and as far as I can tell the shroud is screwed onto the threaded end of the barrel, and when that nut at the very end is tightened, it tensions the barrel and pushes the shroud against the receiver.

If I ever am at the point of looking for something to fill my time, I might try to design and print an active/sealed shroud. I think it could hold up fine with good thread orientation, especially with the compression from anchoring it to the barrel / receiver. This would also require venting in the nut that attaches it to the barrel - it should be possible to 3-D print a very durable solution, or use one of those screw-in metal threaded inserts or some other solution that screws on the end (I can imagine building something around a hatsan airstripper, for example)

Yes, it is tensioned and I think that is why this pistol is more accurate than the rifle.

I think that a printed shroud mod would also work. A one piece shouldered insert for the shroud and an adapter with channels. If the adapter were printed in acetal or PEEK, I’m sure it would be tough enough to tension.

 

[Nutcracker]

Yes, it is tensioned and I think that is why this pistol is more accurate than the rifle.

I think that a printed shroud mod would also work. A one piece shouldered insert for the shroud and an adapter with channels. If the adapter were printed in acetal or PEEK, I’m sure it would be tough enough to tension.

Think that may have a positive effect on accuracy. I used to shoot PB handguns a lot and my Dan Wesson 44 mag was more accurate than my Ruger's, or S&W 29. I thought it was because I could get a tight barrel cylinder gap with the easy to remove barrel. But the tensioning of the barrel VIA the nut on the muzzle in the shroud, probably was another positive influence. Similar to the GK1.

 

[Squirrel hunter]

New grip installed.

 

[dflo]

Thought I would add to the info. I was curious how much it would vary with different ammo weight. Using GK1 .25 v3 as shown below with a cheap chrony on the mod that seems to be good enough for my use, although a few shots didn’t register. Not sure exactly which shots didn’t but the groups were clear from the numbers. Another quarter turn should put those heavies over 800fps, but no adjustment was made in this sequence.

Starting pressure 31MPa

H&N 20.06gr
915.8
901.1
901.1

FX 25.4gr
840.0
837.7
x

JTS 29.63gr
796.7
797.7
x

FX 34gr
764.2
767.1
x

H&N 20.06gr
( just to see difference from starting shot )
889.4

Ending pressure 23 MPa