Here is an other spin off thread for the Huben pistol where members can share what ammo they have found works good,....... or bad in their hand cannon.
Huben Huben pistol ammo choice.
- Thread starter Nomadic Pirate 66
- Start date
These groups were with the rifle, the k1. I know it's a gk1 thread. I have both. But yeah, that up and down pattern makes me wonder if I'm getting some variable velocities that cause it. I didn't use the crony today. I've already polished my 22 k1 barrel. Didn't help with accuracy but didn't hurt either, but it seemed to make the velocities more consistent
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Quick update. I took apart my 25 k1 to polish the barrel and when I did I found out I have an alignment issue with the barrel and mag. In the process of trying to fix it now. Have never adjusted the alignment before. when I get it all back together i imagine it will be shooting much better groups.
Ok got it all back together and will test again soon. Put a slug in the magazine and pushed it almost all the way forward, then put it on the barrel with the slug in the barrel to align. Tightened everything down, removed the magazine and slug, then put magazine back on. Worked perfectly
Ok got it all back together and will test again soon. Put a slug in the magazine and pushed it almost all the way forward, then put it on the barrel with the slug in the barrel to align. Tightened everything down, removed the magazine and slug, then put magazine back on. Worked perfectly
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You need to measure correctly. I used a set of precision pin gauges. The number s were .250" Go and .251" No GO. Please also note that the rear of the magazine bores are beveled to accommodate The oversize lip of the pellet. The front and back of the magazine is NOT the same. I also measured the barrel and the lands were .247 Go and .248 no GO. Now, measure your pellet. The pellet I use has a head diameter of.248" and the skirt is .260".This gives perfect guidance in the barrel and .006" rifling bite for good grip and sealing.
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@steve-l The problem would be that I don’t have a pin gauge set. Especially for a quality set 
, they’re well outside my current budget. Do you have any theory why people are having better results with larger diameter slugs? Or do you think your particular GK1 has a more narrow mag/barrel? Seems like ~.2475 (based on your go/no go results) is MASSIVELY off.
Edit- apparently you can buy really good pin gauges individually. Ordered for .247 through .254
, they’re well outside my current budget. Do you have any theory why people are having better results with larger diameter slugs? Or do you think your particular GK1 has a more narrow mag/barrel? Seems like ~.2475 (based on your go/no go results) is MASSIVELY off.Edit- apparently you can buy really good pin gauges individually. Ordered for .247 through .254
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I have a machine shop, so having pin gauges is a necessity for me and unaffordable for the normal GK1 user. It only takes a few minutes to make the measurement and most machine shops would check this for free if you asked nicely. I do not think my measurements are off at all and inconsistent with other's observations.@steve-l The problem would be that I don’t have a pin gauge set. Especially for a quality set
Edit- apparently you can buy really good pin gauges individually. Ordered for .247 through .254
First, you just want a light touching at the pellet head and a healthy rifling bite at the skirt. This is exactly what my measurement say I have. The danger comes when shooting slugs because in an air weapon you don't have 30,000 to 50,000 CUP that you have with a PB weapon to overcome excessive bore resistance. With my GK1 anything over .253 is excessive.
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Lucky bastard
, sometimes I dream about leaving white collar… But back to the subject at hand, John at NEAG said the same thing as you and advised against slugs for the exact same reason. I wish JSB offered the Monster in .25 to maximize weight while minimizing bore friction
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Keep in mind that some slugs, usually cast ones are likely to have antimony added, making them harder and the diameter a bigger problem if too big. Swaged slugs are more likely to be pure lead and softer.
Any chance the v1 gk1s have a different diameter than the later versions? I have a v1, and it shoots 254s just fine. I haven't tried a 250 in it.
I haven't ever actually measured the rifle's bore diameter either, but I can tell you that .250 slugs shot out of it make a spread at 25 yards that's worse than some shotguns I've seen, and 253 and 254 are much better, with many other people I've seen having the same experience, and observing that 254s are most accurate (in the rifle at least)
Any chance the v1 gk1s have a different diameter than the later versions? I have a v1, and it shoots 254s just fine. I haven't tried a 250 in it.
I haven't ever actually measured the rifle's bore diameter either, but I can tell you that .250 slugs shot out of it make a spread at 25 yards that's worse than some shotguns I've seen, and 253 and 254 are much better, with many other people I've seen having the same experience, and observing that 254s are most accurate (in the rifle at least)
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Bernie,Lucky bastard
But back to the subject at hand, John at NEAG said the same thing as you and advised against slugs for the exact same reason. I wish JSB offered the Monster in .25 to maximize weight while minimizing bore friction
View attachment 414532
I'm a retired computer professional by trade and a machinist/inventor/mechanic by hobby. My machine shop is pretty complete, but then I'm not married! I think slugs are OK for PCP weapons, but they require drive rings just to avoid excessive resistance. Please also note that 22 rimfire bullets have drive rings for the same reason. Consider the JSB 39.4 gr pellet. They are a great compromise and work well to 100 meters, which is way more than required for a pistol. You may also note that the barrel twist I measured on my GK1 is 1 in 16", which does favor heavier projectiles.
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Fast twist, if that is indeed the case (and GK reports a different rate), allows heavier slugs to reach a higher stability factor. Diablo pellets are negatively affected by a fast twist rate because RPM declines slower than speed and they can experience dynamic instability, leading to spiraling. This is also affected by the center of mass, pellet length and BC, the latter two of which are higher with heavier projectiles. Higher BC increases the ratio of decline in speed relative to spin, enhancing the likelihood of spiraling. It is most often reported to occur with heavy pellets, such as JSB monsters. GK provides a nice explanation of the conflict between aero and gyro stabilization of pellets:
Regarding the bore size, a previous poster (@Airgun-hobbyist; post 133) slugged the barrel at 0.253. All K1 users report better accuracy and cycling with .253-.254 slugs.
Finally, drive bands on slugs are not necessary for the subsonic speeds of airguns and are certainly not of benefit when shot from a magazine into a barrel, whereupon the bands can get hung up in transition and damaged if the magazine and barrel are not in perfect alignment.
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The guy that makes KSI slugs suggested to me that you should "slug" the barrel.
Basically, you jam a slightly oversized slug down the barrel from receiver to muzzle, then use calipers on the slug to measure the diameter of your lands and grooves.
This will tell you what size slugs you actually need.
Basically, you jam a slightly oversized slug down the barrel from receiver to muzzle, then use calipers on the slug to measure the diameter of your lands and grooves.
This will tell you what size slugs you actually need.
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Your info on gyro effect and drag stabilization is correct and your slug dimensions are also correct, but your conclusion is wrong because you are comparing apples and oranges. When I measure the barrel bore with pin gauges, I am measuring minimum barrel diameter. When you slug the barrel and measure slug diameter, you are measuring max barrel diameter or land verses groove. I measured .247 Go and .248 no Go. You measured .253 or .254. Which simply means a .006 diametral difference between lands and grooves. That number I clearly mentioned in my previous posts. Further the JSB 39.4 gr pellet is very happy with a 1 in 18 and 1 in 16 twist in that it does not exhibit spiraling in either my FX Crown or the GK1.
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@Steve-I
Swaging is the process of increasing the diameter of something by compressing it longitudinally. The opposite of swaging is drawing (e.g. through a die). The pressures/accelerations/forces in a PB do swage the projectiles, which means that a projectile which might be slightly smaller than the grooves diameter has its OD increased to the grooves diameter, creating a better seal or contact. The pressures in a PB can do this to a solid slug, but the pressures in an air gun can only do this to a skirt-shaped back of a projectile. In practice, sealing is not that important beyond a certain point. Contact with the grooves is important-ish for accuracy.
Otherwise I'm gravitating towards thinking that for target shooting with a .25 GK1, one would only ever need two sets of ammo: Altaros in 6.45mm (the 6.46mm version is too much) and plain .25 JSBs or similar; everything else is pointless.
Swaging is the process of increasing the diameter of something by compressing it longitudinally. The opposite of swaging is drawing (e.g. through a die). The pressures/accelerations/forces in a PB do swage the projectiles, which means that a projectile which might be slightly smaller than the grooves diameter has its OD increased to the grooves diameter, creating a better seal or contact. The pressures in a PB can do this to a solid slug, but the pressures in an air gun can only do this to a skirt-shaped back of a projectile. In practice, sealing is not that important beyond a certain point. Contact with the grooves is important-ish for accuracy.
Otherwise I'm gravitating towards thinking that for target shooting with a .25 GK1, one would only ever need two sets of ammo: Altaros in 6.45mm (the 6.46mm version is too much) and plain .25 JSBs or similar; everything else is pointless.
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They are not really bands, they are cutouts to reduce the contact area with the rifling. The usefulness of this depends on the power level and at high power levels they might make the projectile less accurate by offering less support and making it slightly tilted wrt the bore axis. If or not this actually happens with the K1 or GK1 - someone else with a 100+ meter range would have to pitch in.
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To be clear, I stated the following:
“Regarding the bore size, a previous poster (@Airgun-hobbyist; post 133) slugged the barrel at 0.253. All K1 users report better accuracy and cycling with .253-.254 slugs.”
I’m not sure why you are stating “you measured….”. I clearly pointed out that Airgun-hobbyist did the slugging! Further, I don’t see how my “conclusion” can therefore be wrong. In fact, I don’t see any conclusion in what I typed. Any conclusion that you might see would come from “reading between the lines”.
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Swaging (/ˈsweɪdʒɪŋ/) is a forging process in which the dimensions of an item are altered using dies into which the item is forced. Swaging is usually a cold working process, but also may be hot worked. A selection of blacksmithing swages. Wikipedia
Swaging can increase or decrease dimensions. It is done all the time when cold forming bullets from lead wire and in every revolver that I know of. It is the sole purpose of the forcing cone at the mouth of the revolver's barrel. Uniquely, the .455 Webley swages the hollow based bullet twice. Once in the cylinder and again in the forcing cone.
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For practical purposes, the AVS slugs in 254 (and likely others in that size) perform just as well as Altaros in the K1. This hammerless (Huben) platform just doesn’t have the accuracy of a conventional high-end slug shooter , which is where the Altaros can shine. At best, the K1 rifle can shoot 2-3moa with Altaros. Anything better that you might see is a function of cherry picking.
Regarding the pistol and target shooting (or hunting for that matter), the issue that looms much larger than choosing the correct slug, is that the GK1 is unregulated. Sure, you can shoot one or two heavy slugs at high power, but then it’s a Korean cliff of descending velocity. The cold hard reality is that, if you want to shoot a magazine or more with a consistent string and accuracy, you need to use pellets and even then, they should not be the monsters.
Since this topic of slugs has become so contentious, I am going to bow out of it. It’s all been discussed ad infinitum for those of us that have the rifles. Because of the myriad issues, I use my K1 rifles as pellet guns because accuracy is my #1 priority. The .22 shoots JTS 18.1s and the .25 shoots Hades. For me, there’s no case to be made for shooting slugs from the GK1 outside of trying to leverage its use for purposes that cannot be discussed in this forum, in countries or situations where a more appropriate device (PB) is not an option.
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This is for Steve, who asked me (via PM) if I “even own a GK1?”. Somehow, he missed my many pics or thinks that I’m using someone else’s pics? So here is something more convincing, or did I photoshop it?
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