OS, on barrel vibration, the other day at the range I fired a few shots with different powder charges. One 'group' was a horizontal string almost perfectly in line while the other was a normal group. It made me think of just that thing. On another occasion with a different rifle and jacketeds, I got a vertical string. Again with a different load it produced a circular pattern. Why when there is vertical stringing does the horizontal component disappear? Or the vertical component disappear with horizontal stringing?
So getting back to 22's, I've had a circle group with a cluster on one side. Was that me or was the barrel vibrating in a circular fashion? With open sights I cannot tell because that could be diffraction and my eyes in the particular light conditions.
https://i.postimg.cc/RVj7Nn74/Rem_Subsonic_HN.jpg
Like this;
https://i.postimg.cc/25t6w23Y/Spiral_Bullet_Path.jpg
Notice that the boolit holes in the ring show yawing?
Does this even happen with a 22 boolit? I wonder whether one could set up a target mid-range with a second target exactly behind it down range to see whether the boolits are landing in the same position on each. How would one ensure the bore is perfectly aligned with the two target centers? That would be the challenge.
A thought that has been running in my mind is to build a steel full length stock and fully bed the action and barrel without pressure but clamped onto the bedding just to see what would happen. I'm talking about making the system so rigid that there can be no barrel vibration at all without putting any stress on it.
The old SMLE when used for long range target shooting would be carefully cork packed in the barrel channel (the barrel channel has cut-outs for just such packing), to control and dampen the vibration of the very whippy barrel. Apparently it was very accurate with selected ammo. It's something along these lines that I am thinking of. Trouble is, I don't think any of my rifles are actually accurate enough for this test, meaning the results may well be lost in the 'noise'.
Anyway, just thinking out loud.