Huben K1 Review And Insight Into Accuracy Problems

Hey Gregor, have you tried these pellets http://www.krale-schietsport.nl/en/munitie/munitie-luchtwapens/airgun-pellets-eun-jin-samyang-5-5-mm-32-grain.html and http://www.krale-schietsport.nl/en/munitie/munitie-luchtwapens/airgun-pellets-eun-jin-samyang-bolkop-5-5-mm-28-4-grain.html

Hello!

I have tried most (not all) but the same pattern is seen with all of them - they are not stable. This is due to not fast enough twist rate of the barrel in Huben (1:17,7"). I have replaced the barrel with .22LR (also from LW) that has 1:16" twist and the pellets are stable now. Now I use easy available JSB Beasts that are not too expensive but in order for them to be stable, I have to push them over 1000 fps. Now I have the regulator set to 170 - 180 bar and I get 325 m/s (1066 fps) with 34 grain JSB beasts and they are accurate and stable. That is what I was hoping for and on last Saturday I shoot 2 - 3 cm groups in heavy wind at 70 meters I will post a video shortly...

If that barrel is a .22 long rifle firearm barrel the bore should be .223-.224, pellets are sized for .217-.218" barrel. You may get better accuracy by shooting .224 bullets. Also how hard was it to change the barrel, did you have to line it up with a magazine chamber? Regards, Tom

LW .22LR barrels are sized same as air rifle barrels:
land .215 groove .221 

http://www.lothar-walther.com/375.php - rifles
http://www.lothar-walther.com/457.php - airguns

I have one of recent Hubens, it has what very much looks - LW air barrel with 17.7 twist, 12 grooves





I tried JSB Beasts at 304m/s(1000ft/s) and up to 50m they group ok. Yet to take it out for longer distance. 

From what I see difference between LW air and .22LR barrels is twist rate 17.7 vs 16.4 and grooves 12 vs 6. Twist rate difference is 7%.
By bumping up speed 7% you will be getting same twist rate. 

JSB Beast is 10.7mm long .22LR is about 17mm long. Beast is 30% shorter.

Gregor, are you sure that your pellets are spiraling because of imbalance cause by twist?



JSB Beast is shorter & lighter than most of .22 bullets, .22LR barrels existed forever and have twist rate sorted out long time ago. 

Hard to find any numerical reasons for under stabilization.


In powder burning world - lighter/shorted bullets can be stabilized by given twist and as you go heavier imbalance starts to show up.
According to that light classic pellets should NOT spiral. Unless they are over-stabilized and have barrel distorted skirts.


Looking at my Huben I think there are other reasons for unstable pellets - aka baffle/shroud distortion.

Peole
Have you verified your thinking by shooting the gun without the Shroud? Gregor is shooting his new 22LR barrel without the shroud, so you might have somthing.
If the weather will allow I will do some long range shooting without the shroud this weekend to see if it has any change on my groups.

My gun does not have a threaded barrel at the end like yours does. so some things have changed in the final shipping product.

Wlbryce

I only have 50m by my house. And at 50m I do not have gross spread, so I think removing shroud will be inconclusive. My shroud is finder tight.

I need to get out and try 100m.

Here's my scope zeroing at 50m, I'm sure once I'm done with zeroing it can do better:

I have been following these posts for quite some time now on the huben and I finally was able to get my hands on one I have had very good success having the regulator set to the lower end of the spectrum and the velocity adjusted to about 850 to 900 feet per second. The only pellets it seems to like at all for me are the h&n baracuda 21 grain pellets

Tom Gaylord (unfortunate name) wrote a really long piece on the PA blog about twist rates in air rifles. He did what he claimed to be the only actual factual test on this using the same air rifle with 3 different twist rate barrels at 3 different power levels. One of the barrels was the Lw that came with his Air Force. 

I can't remember what his conclusion was because the article went on for 10+ pages and I got bored but he definitely came up with some sort of conclusion. May be worth taking a look before changing the barrel. 

I am also fairly sure he said something about how Diablo shape pellets have additional flight stability over regular bullets due to the skirt. Perhaps the logic used for bullets and twist rates isn't 100% transferable to pellets. 

Either way, if I was going to buy a .22 semi auto air rifle, I would probably go for a Revolution, Monsoon or Max over this. Not being able to change the mag is a horrible idea. Semi autos are for rapid firing. Plus I hate problems and I definitely don't want to being buying a new barrel to make any air gun work properly. 

Also the Steyr Hunting 5 semi-auto.

"Steyr"Also the Steyr Hunting 5 semi-auto.

Click to expand...

Not sure about that one. I am a fan of Steyr products on the firearms side but not so much on the air guns side. The name means more to the precision target shooting market than it does to hunters and recreational users. 

The Hunting 5 looks nice enough but at $3,000, I want more information than what is currently available before I would even think about considering it. The sales pitch seems focused on selling the general benefits of air guns to firearms users instead of telling me what is so good about the Hunting 5. I can't really tell why I should pay an extra $1,000 over the FX Revolution, or an extra $1500 over the Monsoon. The FX has a larger reservoir, larger magazine capacity and is quieter out of the box. The Monsoon is lighter too. FX barrels are accurate. More than accurate enough for hunting. 

Imo, Steyr needs to borrow a little innovation from the firearms side and take a look at the market before pricing their hunting air guns. For example, Steyr started using carbon fiber sheet molding compound for their precision rifle stocks. Why can't they use it for their air guns too? Sheet molding compound is easy and cheap to use and there is always a market for lighter stocks.

Also, bullpups are very popular with air gun enthusiasts right now. The Steyr AUG stock is one of my favorites. If there was a semi-auto Steyr AUG PCP rifle with large capacity mags, regulator, LW barrel and CF sheet molding compound stock for around $1500 (in 25 cal) they would fly off the shelf. I am making a cf Steyr Aug stock for my Cricket which I intend to use as my main stock because they are awesome.

As it stands right now, the Hunting 5 is an obscure product for a tiny number of users imo. Who is it aimed at?

As an FYI, my carbon fiber Steyr Aug stock for my Cricket:

http://postimg.org/image/46gp935oj/

still needs sanding, trimming and the bedding block to attach the Cricket action but you'll get the idea. You put the Huben, Monsoon or Hunting 5 action in that and I'd buy at least one....

Oh my! That is beautiful! What does it weigh?

Hi.

Azairgunner
You have the exact same results as I do, baracuda match are the only pellet I have tested that works OK in Huben with stock barrel.

peole
I am quite sure that the twist rate is the problem, now that I have changed the barrel. Here is my video where you can see my results:

I have not yet seen a .22LR slug that is 17 mm long so I do not know what you mean by 30%. Keep in mind that you have to measure only the slug, not the whole bullet...

Faster twist is required when the slug gets longer but even faster twist is required if the slug is linger and lighter at the same time. Rotating mass is what stabilizes the projectile, having more mass in the outer side of the projectile helps,....

Pellets (even JSB monster) are usually somewhat hollow, that means that they are lighter compared to their length that slugs, and that means that they require even slightly higher twist rate.

Increasing speed does spin the pellet faster but bigger speeds also creates more instability because of being closer to the sonic speeds that are know for its stability issues.

I you watch my video, you will see that ever with 1:16 twist (.22LR barrel) pellets are not stable if they are not fast enough (under 300m/s)

Standard pellet shape however has another way of stabilization. You might notice that shoot gun slugs are usually the same shape (there is a reason for that) and they are relatively stable in a smooth bore... They have heavy front head and light hollow tail / skirt that has a lot of drag. That means that they stabilize in similar way as arrows. This stabilization with additional non aggressive twist rate of the airgun barrel is enough to make conventional pellets stable but as soon as you put in a slug on a pellet that does not posses those features they will be unstable. and example is JSB Monster. This pellet is basically a slug by its shape and I have not seen an air gun that would shoot this pellet well. It does not ever work well in the .22LR barrel because it is too light for its length and it would require an even faster twist.

It would be great for huben to have even a slightly more aggressive twist than .22LR but there is no barrel (from LW) that would have an appropriate dimensions and higher twist rate.

Gregor, your effort is highly apprecicated. 

But I'm still wondering why an airgunner prefers an airgun to a firearm.

For most of the airgunners, does it make any sense to turn an air rifle into a rimfire? IMO,the Ruger SR-22 rifle that costs only 700 US dollars is way better than the modified Huben k1 with a LR barrel. 

"semieros"Gregor, your effort is highly apprecicated. 

But I'm still wondering why an airgunner prefers an airgun to a firearm.

For most of the airgunners, does it make any sense to turn an air rifle into a rimfire? IMO,the Ruger SR-22 rifle that costs only 700 US dollars is way better than the modified Huben k1 with a LR barrel.

Click to expand...

It's not an either / or. They do different jobs. 

I would never ever use a firearm in my back garden. They are too loud and the neighbors would call the police. I prefer firearms for hunting larger game though.

Good air guns are accurate, quiet, no recoil and have far less legal hassles these days. This is especially true for certain states. I live in New York where people are literally having to saw the pistol grips off their firearms to make them legal. Plus, there is no chance of getting a license for a silencer or short-barrel firearm where I live. 

The energy thing is irrelevant for many users as it's wasted. Once a pellet or bullet has enough energy to hit the target, penetrate and expand, the rest is over-kill. My .25 PCP guns are powerful enough to kill any small or small medium sized game at any distance I could actually hit them at. I often avoid using some of my more powerful air rifles because they are loud and I have no need for their extra juice. A guy in another forum hunts hogs with a .22 PCP rifle and has no issues dropping them...

Shooting an air gun is just more relaxing and enjoyable for target shooting, plinking and small game hunting. Ammo is cheap and easily available. They aren't much good for target shooting at 1000 yards though....

Here is my answer to: "why an airgunner prefers an airgun to a firearm"

Two reasons:
1. I live in EU in a country with relatively strict gun control policy. It is legally much easy to own an air gun than any firearm (even .22LR)
2. I am an applicable physics enthusiast and I love to go to the limits of a certain technologies and try to achieve maximum efficiency. For example: .22LR has over 10 times larger pressure than Huben does when fired but it still can achieve almost the same energy. I agree that all this could be achieved easier with any firearm, but easy is not challenging and is not what I am looking for

Here is my take. I'm 54 and have been shooting from about age 20. Been to many combat rifle matches over the years. Shot AR15 and M14. I reloaded everything I shot and enjoyed it all those years. This sport became more and more expensive, and more and more regulated. Got into Airguns about 24 years ago and was hooked. Suddenly I could shoot in my backyard. I could eliminate pests silently and have fun doing it. I could shoot something that was expensive up front but very cheap to enjoy down the road. Last was the craftsmanship of air rifles is something to behold. Just holding a top quality air rifle and seeing how well they are engineered and assembled is amazing which is another huge fun factor.

Interesting rifle and 2 informative threads on it.

An out there question perhaps: can the FX ST be fitted to the K1?

Any .22 barrel could be fitted, but it would probably shoot well only with low powers and energies. As far as I know (I have never tested an ST barrel) it does not do well with high powers...