A custom bullet mold for Huben K1

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I looked at these and they are a similar design as the Varminter, but more rounded nose and not HP's. I didn't see the length on the website.
When you mentioned that it is more like a revolver that made me think about how the rounds enters the barrel. If it is a loose fit then the accuracy may never be there, and the only way you to get it is to have a slight interference between the bullet and barrel, so the barrel will straighten it out during flight. Maybe .0005 larger than the barrel so the round makes full contact.
The other thing is with the max length of 11mm, there will be a finite weight that can be achieved with the 5,62 dia. and 11mm length. At these velocities we will need a heavy round to bring the fps under 1125, so we are below the sound crack, and have max ft-lbs of energy.
This is what I need for Hunting, and looking forward to the semi auto design of the huben, hopefully we can figure this ammo issue out without too much out of pocket.
I should be receiving the cast bullets soon, so I will let you know the length, and Dia. unfortunately I can't test them, no Huben!!! 
 
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I have the information about the length... They are not too long (they are not very heavy also. Huben would be able shoot them supersonic for sure (it can shoot 34 gran JSB's supersonic)... If anyone tested them, please let me know how they preform...
Huben has as perfect aliment as possible of the magazine and perfect seal the pellets or bullets are not deformed in any way (I have fried several bullet into water and examine them...). They have done a good job in that regard. I have even recorded in slow motion and it really preforms flawlessly.
You can get 40 grains with 11 mm length in with reasonable BC. But most bullets are just a fraction longer :(
You can send me some cast bullets to test ;)
 
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Hi

I am currency waiting for a new mould to arrive and to test it.
I am just in a phase of testing the NAA CBB bullets (thanks to my friend form Florida), so far the results are very good but they do need to be sized in order to fit them in the magazine. I have made a sizing die .223 that is perfect because the bullets still have a snug fit in the magazine but it is possible to insert them with fingers...

I will send more information / pictures when I am finished with testing.
 
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Sized some of the CBB bullets to .2195, seemed lkie as much as my choked barrel would take. (Had a bit of a hang fire at shooting at reduced power for easier pellet capture, about a 1/4 second delay between launch and clearing the choke.} Driven through the sizer nose first, the trailing portion showed uneven finish to the rifling marks. Sized skirt end first, looks to be cleaner finish of the rifling engraving. Loose in the magazine at this size. No winners yet in the accuracy department, but more testing to go.

A mold for casting .22 arrived today. 22lrreloader.com/design-details
The shorter cavity makes 25 grain, measures .217-.218 at the forward flanges. I intend to tool the mold to add a flange at the trailing edge about .224 to locate in the cylinder. The idea being that at firing, the last flange gets folded back making a bit of a skirt. We'll see how it goes.
 
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Promising modification of the CBB cap and ball bullets:
1. size down to .217 in a die cup end first using a cup end punch to push on the bullet nose
2. flare the cup end out past .228 by standing on a flat plate and driving down with a punch conformed to the bullet nose
3. size the flared end down to .228 in a sizing die
Finished length runs.299 +/-.001

Despite the cheesy setup- some dings on the noses, the possibility of tilting the base in the flaring process-- I got a one inch group of five shots at 30 yards that included three holes overlapping, shooting bucket and sticks. (Sorry, no longer range at home.) Regulator at 15 mPa, adjuster open 21 clicks.

The heavy flare at the base locates the bullet securely at the breech end of the cylinder, giving a concistent power cycle, and extends the baseline to limit tilting off axis. Driving point end last in the initial sizing also extends the baseline.

I'm not saying this process is worth doing regularly, but it may indicate a desirable form.

Photos: unmodded bullet, modded, modded and fired into a phone book at 45°; the group and a modded bullet for scale.



edit:better quality pics of same pellets:



Pellets seem to lengthen 5 thousandths on exiting the barrel. Substantial leadding of the barrel encountered..
 
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Hi Gregor,
Firstly I want to thank you for your very informative and helpful videos on YouTube relating to the Huben K1, excellent!
I have ordered my Huben K1 and expect to receive it in the new year. I live in South Africa and would like to let you know that I am very interested in your custom 5.5mm 40grn mould, so please continue with your development.
I am aware of a company called African Air Ordinance that have a custom 5.5mm mould for sale, and see that it is a flat base, and can be manufactured to any lenght or diameter. They have a 40grn bullet/pellet that is 11.5mm long, however it can be changed to 11mm long, which will give you about a 38 grn bullet/pellet.
Take a look at the following: http://www.africanairordnance.com/424820687/product/2025131/5-5mm-40-grain-round-nose-bullet?catid=625380
I have ordered 100 x 34grn pellets, ready to test in my new K1.
May I ask, if you are still impressed with the Huben K1?
Regards Malcolm
 
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Hello Malcolm

I am still working on my mold, however I am afraid that no bullet shape will realy work accurate in the stock barrel at least not at long ranges. My first attempt of the bullet was slightly to small and the boat tail was not accurate enought due to the plate that cuts off the excessive lead form the rear of the bullet... I will get 3 new designs of the mold coming up in in January along with a new cutting plate that will have smaller holes now, and it will not deform the boat tail as much. I have also made a sizing die that I will use for sizing them to 5,67 - 5,68 mm. This is the perfect fit for the magazine.

I have been shooting a lot with CBB++[/QUOTE]https://northamericanarms.com/shop/parts/cbb3/embed/ lately. They preform great with my custom barrel as long as the velocity is under 300 m/s... They do need to be sized thought to fit in the magazine... They work rather well in stock barrel as well as Cernunnos discovered (thanks for this input!)
 
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Hi Gregor, unfortunately for me, I have to stay below 5.6mm due to South African firearms regulations. If the caliber is 5.6mm or above we are only allowed 8 joules without a firearms license, however if the caliber is 5.59mm or lower there is no need for a firearms license no matter what the energy is, so I will keep below 5.6mm.
Are you still impressed with the Huben K1?
 
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Hi.

The caliber and the dimensions are not always the same. Most .22 are called 5,5 or 5,56, that does not mean that the bullet is 5,5mm. Actually, the grooves of and airgun barrel are 5,62 mm meaning that the pellet when it exits the barrel has a skirt 5,62mm... I am pretty sure the the the bullets you are looking for are actually .224 or 5,69mm. So I do not think that should be a problem. BTW: if you are going to use a bullet in Huben, you need to make sure it has a thigh fit in the magazine or it will not shoot accurately.

Yes I am still very satisfied with Huben. I had problem with it (a spring broke on the magazine indexing mechanism) but I got the spre parts form my dealer right away. I think that for regular user this gun may represent some getting used to since in uses totally different way of operating and a user do need to get used to it. To put it in other words, the way operating safely with this gun is slightly different than with other PCPs. Personally I do not have a problem with that but I do understand the gun in detail and I hope that user watching my video will too. I think that Huben should take care of that instead they are almost keeping it a secret...
 
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Hi Gregor,

first thank you for all the information you put on the internet about the huben. I would be more than interested in a custom bullet mold. Anyway today I have tried some wasp magnum .22 in my huben which I got from my local gun store. As far as I am concerned they do not sell these bullets anymore at their gun store and they had this open tin for a long time on their test range which I could have. At first when I measure the bullets I did not think they would fit in the huben cause they are 5,65mm in diameter but when I tried they do fit in the magazine just like you said they do. I don't know if you have tried these bullets but they seem to work well in my huben which has a replacement barrel to.
Btw here a small summary of the specifications of the bullet.
wasp magnum .22
5,65mm in diameter
9,20mm long
30.2grain
Distance I was shooting was 25 meters. First group of 3 where at 267m/s 11MPa, second group of 3 at 288m/s 13,5MPa. I will test them soon at 50 meters and with an other scope so I can see my target better, and maybe with other adjustments on the huben. However I need to be thriftily because I have just a few of these bullets left and I don't know were to find these bullets for sale. Here are some pics of the bullets and groups I shot. (btw MPa should have been bar)
 
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