Full demo with a beautiful Skout Epoch. This will work with ANY airgun barrel that can be indexed (spun). Thanks for watching! -Nate
" This will work with ANY airgun barrel that can be indexed (spun)"
Sorry Nate, but that is not true.
Indexing works like this in the Skout because the barrel is not free floated.
Barrel is firmly supported at TWO points: shank and end of chassis. So the "free-floating" section is VERY short.
On MOST airguns that have "thimbles" which is the piece that attaches the barrel to the breech AND serves as a transfer port (where these are used), the barrel is free-floated for most of its length. Under these conditions, "indexing" the barrel actually serves other purpose: to align the internal stresses of the barrel with the support points/forms of the specific rifle. There are rifles where there is no "thimble" and, yet, the barrel can be indexed because the air is moved through other components, like the Steyr where the air is moved through the bolt, or the Thomas, where the air is moved through the basculating breech.
When a barrel is rifled, with the exception of those barrels that are made by ECM/EDM (and these are very far from being mainstream), the machining operations create internal stresses. Stresses that are not always easy, or possible, to "relieve". This creates sections of the steel that are more " internally tensioned" than others, and so, if you align those "high-strung fibers" to the attachment method used by the designers to attach the barrel to the receiver/chassis, you get increased precision.
In YOUR case, what you are looking for is increased accuracy, and that is achieved by "aligning" the POI's across opposites sides of the barrel's natural POI's per index point.
Now, if you think about it, if you are interested in long range shooting, then you should choose the setting that gives you the HIGH position group (IF all other groups are equal), because this is where the barrel is shooting "flatter", requiring less elevation from the sighting system to achieve the same POI.
No doubt the Skout is in a class of its own, the valveing, the barrel attachment, and the construction of the barrels themselves is interesting.
Perhaps when I grow up I will get one. 😉
Thanks for the video and for making me dig deep into the Skout's architecture. Keep well and shoot straight!
HM
@hector_j_medina_g Thank for for all that awesome info! I was wondering what a high end manufacturer does when thier barrel is fixed. That is fascinating stuff! I will probably read it a few times. Thank you. -Nate
P.S. I have a Steyr LG110 High Power but have nto shot it much. I need to!
I learned a new term: "basculating breech" It's interesting that this design has been around for a very long time!
MLM
P.S. I have a Steyr LG110 High Power but have nto shot it much. I need to!
Thanks for your kind words. I really enjoyed getting into the Skout's diagram on that end. I had studied before the valveing system, but had not caught that the chassis is a forward support for the barrel and that they have a bushing and a nut in there.
Again, thanks for your videos.
BTW.- The LG110 really shines in 0.20" cal.
Keep well and shoot straight!
HM
I learned a new term: "basculating breech" It's interesting that this design has been around for a very long time!
MLM
Yup! Peculiarly, applied to airguns, it has been VERY prolific in the far east (Phillipines and Malaysia, mostly).
When LD picked it up for the Simple Simon and then the USFT a few decades ago, it became known in the US, then Thomas used it and it is now mainstream.
It is an efficient system to transfer the flow of air to the barrel, not the most efficient because that distinction belongs to the "in line" systems, but close; and allows a number of interesting things, "indexing" being one of them.
I would suspect all Thomas rifles get indexed at the factory, though I have not read/heard that this is so. Steyr tried, but it became too onerous a process at Austrian wages.
Hope you're doing well in your travels, keep well and safe return!
HM
Not sure about which category you are referring to:
YOU tell me:
Basculating breech? Yes:
Indexable barrel?
Hard to tell from the diagrams available but I would say it does not need to be.
And the reason is that the barrel is a spaghetti barrel inside a shroud:
http://snowpeaksports.com/filedown/index/73.html
AND there is a nut at the end that affixes the shroud, but that nut can also be used as a tensioning device to "tune" out any possible harmonics. This nut also serves as an airstripper, so it COULD be replaced by a full fledged LCD,
If you look at the diagram, barrel (part #4) is retained on one side by a nut (Part #5) that is called the Barrel Sealing Block. In essence, this block is a thimble.
Whether the barrel is indexable or not depends on whether the attachment of the barrel to the thimble allows for rotation or not. From the pictures on HUMA's website it would seem that both ends of the barrel are threaded, and the transfer port is located at the "Movable Joint" that is part 21. So, while part #7 is shown to have a "flat", I assume to hold the position when attached to the frame, it would not be illogical to suspect that the cavity for that part is cylindrical, and therefore a part made to be rotatable could be used to index the barrel between the frame and the muzzle.
From the practical standpoint, I wouldn't attempt it as a pistol. It is an interesting pistol and, given the reports of them being capable of reaching 20 ft-lbs in 0.22" cal even from a short barrel, they would seem to make an ideal carbine creating platform.
Only in such a case, would this merit some exploration because a longer barrel would indeed profit from indexing once the muzzle is well past the support point of the shroud/frame.
HTH, Keep well and shoot straight!
HM
I don't have pictures since everything was aligned right on my Hubens, but there's several mentions from Gregor Kamenšek in his YouTube disassembly/reassembly videos that detail it more. I've only had to partially break down my K1 a few times to deal with jams, so far so good on the GK1.
This was one section from the GK1:
*The time stamp should be at 23:18
And another from the K1 disassembly which describes the adjustment process and shows more detail:
*The time stamp should be at 15:14
THANKS!
Interesting that these guns are, really, revolvers, LOL!
From what I understood, Gregor is talking more about the indexing BETWEEN magazine and barrel, rather than the indexing of the barrel itself around the bore's axis.
In "formal" gunsmithing the indexing between the cylinder that holds the rounds and the barrel through which the projectiles pass is called "timing", so in these two cases, what Gregor is talking about is the "timing" of the cylinder to the barrel. I do not see clearly the magazines, but they do not seem to be rifled themselves. They just present the pellet to the barrel's leade, which is where the rifling starts.
What we were discussing here is the indexing of the barrel to its OWN axis (boreline).
Now, in the videos, it shows that the barrel is attached somewhat like the Savage series 11 and successors (100, 110, etc) rifles attach the barrel to the action, and that is with a thread that affixes the barrel to the action and a NUT that regulates the "gap" between action "walls". In the case of the Savage bolt action, one wall is the bolt face, the other is the datum line for the bottleneck cartridge/rim thickness that defines the "headspace". In the case of any revolver, you do not have a rear "headspace" because 90% of the revolvers use rimmed cartridges, and those that do not use either "full moon" or "half moon" clips that ENSURE a rear headspace. BUT the MOST important adjustment in building a revolver is the "cylinder gap" and that is the small sliver of space between the MOUTH of the cylinder and the barrel's breech that leads directly to the "forcing cone".
In those revolvers that have been made to have interchangeable barrels (Dan Wesson, mainly), a slip gauge was provided to set this gap.
This gap cannot be "zero", because powder fouling would accumulate and "freeze" the revolver, rendering it useless. SOME designs (like the Belgian "Pieper"), made the cylinder go forth to seal into the barrel, then retract and then rotate. Sadly, the powder residues accumulation still created problems and the system was dropped.
In airguns, there is no residue and you can always fit/use a face Oring (like the old Crosman 262's), and ensure proper seal between barrel and magazine. Steyr also uses a face Oring in their Auto-5's and Auto-10's, as well as in their LP5's.
From what it seems in the video, indexing of the barrel is not possible because turning the barrel would change the cylinder gap. And the gain in precision would not be enough to offset the loss of energy/pellet jump through the gap.
Thanks for posting the videos, I learned something today and that is always a good thing!
Keep well and shoot straight!
HM
