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Just amazing how airguns have improved over the last 15 years or so.

1 hour ago, fourtyvoats said:

I see this often, Very good groups but they move around. Why? Are you adjusting the point of aim?

Ahh yes, I was playing around with my scope - not particularly interested in where they were going, just looking for group size.

I shot a few groups with R50 today with my Annie54 at 50 yards. These were shot at Bisley on Melville range, a really crappy day. Quite pleased with the R50 used on the top four diagrams, the middle two were Centre-x. Looks like the R50 just had the edge there. No spectacular by any means, about .7moa average I guess.
All 5 shot groups at 50yds,  25yd prone target, front rest, glove at rear. 1976 Match 54. R50 and Centre-x

2 hours ago, No i deer said:

I see f class John's new video includes 200yds 22lr match and he is rock steady off his br set up in a tail wind.

His rest/bag set-up seems remarkably steady - A far cry from shooting off the 1/2" ply wobbly tables that are often available.

Don't they work on totally different principles - A tuner is used to manually vary the PC to the desired distance. The "Limbsaver" is a de-resonator, i.e. designed to deaden the barrel so it doesn't ring like a tuning fork.

I would think the position of a de-resonator would not be critical, as long as it's not positioned at the natural primary null point or about 6 inches from the end of the average barrel. Of course, the damper system wouldn't give the benefit of PC at a tuned range - on the other hand it wouldn't be so range sensitive. De-resonators or mid barrel dampers are often to be seen on long barreled battle tanks I believe. 

12 minutes ago, terryh said:

But one comment re null points, some BPCR shooters use a rest near the end of the barrel counter to common practice. I believe they put talc along the top of the barrel, tap it, see where the talc piles up ( I.e. a null pint) then put a bit of tape at this point as the ref. to rest on?

In the vein - has anyone any experience of approaching the problem from the other end and trying to deaden vibration altogether i.e. Limbsaver de-resonator style ?
I'm thinking about putting heatshrink tubing on the full length of the barrel. Although a "dead" barrel won't have the benefit of PC tuned to a fixed distance it might be interesting to try.

I really think we are only scratching the surface with our understanding of barrel vibrations - lots of theories and anecdotal evidence but very little repeatable data.
My own idea is that the muzzle of an untuned, undamped barrel moves in a vertical figure of eight sinusoidal type movement. I believe the mostly vertical component is just due to gravity. I've never tried to measure it but there must be considerable amount of droop with a heavy, long barrel. Take a typical old school heavy barreled .22lr match rifle. The fore-end is quite stiff, likewise is an inch steel bar but it takes only finger pressure to move a floating barrel in the channel. I think if you were to measure the clearance gap, then turn the rifle upside down and measure again there would be a measurable difference. 

Here's a short video demonstrating "null" points in a metal rod..

Excellent - better ignition should lead to lower ES and better down range consistency. - Would have been interesting to chrono a string with the same ammo before and after.

21 minutes ago, Big Al said:

. My 1000yd load was hopeless at 600yds for example and vice versa.

 

Hence, my old Dad, who was a keen traditional Bisley target shooter in the '50-60's had two rifles, his 600 yd rifle was a Fulton regulated Enfield No4 and his 1,000yd rifle was a Mauser action P14. Although all ammunition was "as issued" and no "tuners" at that time it was an established fact that the P14 had PC more suited to the longer ranges.

1 hour ago, Big Al said:

I can tune both rimfire and CF barrels using a tuner to show vertical groups, horizontal groups and then round groups using ammo with typical variations in velocity.

Velocity variations are irrelevant if you tune a barrel to a fixed distance using the positive compensation method.

Indeed - Positive (and negative) compensation has been recognized for many years. Quite well explained in "Target Rifle Shooting" by Reynolds and Fulton 1972. Although mostly relating to regulating the service rifle for target shooting, the theory was well understood.

52 minutes ago, fourtyvoats said:

http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/tuning_a_barrel.htm

 

Excellent link. Finally some numbers to support the empirical evidence that some tuners do work. Having resisted the temptation to invest so far, can any one on here recommend one for a short barrelled(18 inch) Anschutz 1408EDS(Running Boar Rifle repurposed).

More information here:

Rifle Barrel Tuner Vibration Analysis (varmintal.com)

and a tuner coupled with a bloop tube.
Theory • Starik Shooting

1 hour ago, OSOK said:

I am lost for words ....😂

Sorry - I missed the joke there, can you explain?

That certainly looks good vertical.

19 minutes ago, OSOK said:

The vertical dispersion is through the velocity variations within your shots.... Tuners won't have any effect on that !

OSOK

My understanding is, that exactly what a tuner is designed to do. Provide positive compensation to varying muzzle velocity to reduce vertical stringing.
Here's an interesting study on the subject:

Using barrel vibrations to tune a barrel (geoffrey-kolbe.com)

I think a fire case doesn't tell the whole story -  with a light strike that has managed to fire the round I would think there would be an element of fireforming the case back onto the firing pin so may actually look ok. A photo of a misfired live round might give more information.
Those look good strikes, but you are using a lot of pin energy by striking right out to the rim, squashing brass against brass.
This inboard strike is considered by many rimfire benchrest/competition shooters to be a better bet for consistent ignition.
Weak and inconsistent ignition contributes to vertical stringing and high ES velocity.

Serious competitive shooters might take their £4-5k target rifles in for an annual service - The firing pin spring is something that is regularly changed, in most sporting rifles it won't get changed for the life of the rifle.

Photo courtesy Bill Calfee.

This is, of course, where tuners should earn their keep, to compensate for vertical dispersion at a given distance. I feel there's a lot more methodical research needed to produce repeatable results.

Here's some CZ firing pin info you might find interesting:

How about showing a photo of the misfires? Could be light strikes, firing pin shape or position where it's impacting the rim.

My homemade solution to the tuner/moderator problem: Sako Finnfire with Lilja match barrel.

If you want to be nitpicky than you could factor in the barometric pressure too.
It looks as if, as a rough guess, the difference in temperature (air density) between 0c and 20c will show as about 3.5" on the target at 200 yds.

I would think the colder weather accounts for your crackers. All the "target" ammunition (except R100) is designed to be subsonic, usually around the 1,050-70 range. Eley Match and Tenex used to print the velocity of the particular Lot on the box but I don't I don't think they still do.

At 15c the sonic barrier is about 1,116fps but at 0c it's only about 1,086fps. When a string of this, supposing, high quality match ammunition is checked with the chronograph an ES 20fps is not unusual. Personally, I think this is pretty poor, you wouldn't be thrilled to see that with centrefire ammunition at 3,000fps. My regulated air rifle will put out a 10 shot string with an ES of maybe 5fps.

4 hours ago, terryh said:

Alan, the inserts rifled barrel is 23” from breach to muzzle, as you say not supported at the muzzles of the rifle it is used in ( that’s a 32” ish barrel to give a 36” sight radius).

 

Ahh - It must be the 9" internal Bloop tube that accounts for the accuracy.

I'm really interested in that, not quite the same as the old Morris tubes for the Martini-Henry rifles. It looks to be not full length so not supported at the muzzle. Is it just a good sliding fit in the barrel or are there rubber bands of some sort around it?
It's a great pity our laws make it so difficult to experiment with things like this - This would be a fairly easy home shop project to bring and old wall hanger back from the dead.

Very impressive with the Sharps. That seems an excellent result with an adapter tube (Have to think about a tube for my Greener GP shotgun )

That's a nice set of 100yd cards Terry. True, shooting consistently with the .22lr does bring extra challenges but it does seem as if we are reaching the limits of it's capabilities.  As far as I can see, there has been very little increase in accuracy in the last 50 years.
We are probably all more aware of the need for careful selection of ammunition now, tuners of various sorts play their part too, but given the array of associated equipment available to use now, scopes, chronographs, joy-stick rests etc.  we don't really seem to have come far, especially when compared with centrefire over the same period.

I can see the time when airguns will regularly outperform the .22lr in benchrest competitions, they have been steadily improving for many years now and the gap is closing fast.

Here's a clipping from 1960 - remember, these rifles were only ever used with 2.5lb trigger, aperture sights and a sling. I don't think the 100 yd NSRA target size has changed since then.