Moderator as barrel tuner

[brown dog]

Just now, Popsbengo said:

Not at all,  as I said, there's no .22LR data I can find so I've just made a imaginary cartridge that has fast powder, achieves something similar to .22LR in a 16" barrel at the muzzle.  I can't plot anything else as Kolbe's program just gave me that output. 

My two earlier eg graphs compare plotting against time vs plotting against distance.

Against time, acceleration is an S Shape that interpolates to show linear acceleration

... I'm pretty comfy that linear acceleration to 16" followed by constant vel is 'about right' for a .22match round

 I think you're being distracted by the shape of the 'against distance' graphs?

Im still struck that your barrel times so far haven't been significantly different to rounds giving mvs 3 times higher...., and the latest, I can't follow, but it still doesn't seem intuitively right... 

We're into tale chasing without an 'actual' number.   My ancient pirate copy of QL is long gone with the laptop it was on; so I can't play with approximation tuning, I'm afraid.

[Ronin]

Slightly off current discussion

 

Eric just posted this which shows how effective the tuner is 

https://youtu.be/yQNHLnjPqYk

[Popsbengo]

11 minutes ago, brown dog said:

My two earlier eg graphs compare plotting against time vs plotting against distance.

Against time, acceleration is an S Shape that interpolates to show linear acceleration

... I'm pretty comfy that linear acceleration to 16" followed by constant vel is 'about right' for a .22match round

 I think you're being distracted by the shape of the 'against distance' graphs?

Im still struck that your barrel times so far haven't been significantly different to rounds giving mvs 3 times higher...., and the latest, I can't follow, but it still doesn't seem intuitively right... 

We're into tale chasing without an 'actual' number.   My ancient pirate copy of QL is long gone with the laptop it was on; so I can't play with approximation tuning, I'm afraid.

Well, I'll leave it there now, it's been interesting and a distraction from the shut-down blues.  😁

QL is useful but I must say it's a dreadful program from a users point of view  - feels very 1980's 😁

[1066]

These are velocities shot through  3.27", 7",10" and 16" barrels

Remington Subsonic Hollowpoint, part # SUB22HP
Barrel length Average
3.27 766
7 934
10 972
16.25 1016

CCI MiniMag, part #00034
Barrel length Average
3.27 969
7 1126
10 1165
16.25 1243

 

Remington Target Standard Velocity, part # 6122
Barrel length Average
3.27 884
7 1049
10 1099
16.25 1141

[ds1]

1066, I’ve never understood the reason why 22 standard ammunition is produced ( in a 16” barrel @ 20c around the speed of sound .....343 m/s). Possibly way back when, it was only thought to be used out to 25m but now people seem to want to take it out a lot further ........maybe better off with subsonic to start with and not have to deal with transonic problems.......a bit like the venerable 45-70 for long range.

As an aside I also have a Sako Finnfire Range for 22 plinking......I never went to a Lija barrel or geissele trigger however - standard one did fine with a toy rubber car wheel stolen from the kids Lego set replacing the thread protector - a mini dick ring if you will. Still it’s high maintenance- Eley Tenex is its preferred diet ( I can buy 9mm cheaper here).

[brown dog]

8 hours ago, 1066 said:

These are velocities shot through  3.27", 7",10" and 16" barrels

Remington Subsonic Hollowpoint, part # SUB22HP
Barrel length Average
3.27 766
7 934
10 972
16.25 1016

That's bloomin useful data  - I've got a mad day, but later, that can be used to calculate a slightly finer-grain representative acceleration/ barrel time to 16"

[terryh]

12 hours ago, Popsbengo said:

Well, I'll leave it there now, it's been interesting and a distraction from the shut-down blues.  😁

QL is useful but I must say it's a dreadful program from a users point of view  - feels very 1980's 😁

PbG - it does have a BBC B computer feel to it 😉 but pretty straight fwd to use and overall a pretty good tool.

Will have a play with all this information sometime today between bloody Teams meetings.

Going off OP but throwing in a few other things to discuss or exchange thoughts on, we are focussing on harmonics and (possible) the tools to adjust but where do the other metrics associated with 22rf fit into all this, can we just look at one thing?

You have bloop tubes (still air or just sight radius?), clamped barrels with cone breaches to allow you to rotate the barrel to find a sweet spot, mechanical barrel pre stress (e.g. the Freeland stock for a 52E), twist rate (standard 1:16 dates from the horse and buggy era), number of grooves (think current BR record holder used a 2 groove after experimenting) or just plain old bedding (free float, part and full barrel).

[1066]

1 hour ago, terryh said:

PbG - it does have a BBC B computer feel to it 😉 but pretty straight fwd to use and overall a pretty good tool.

Will have a play with all this information sometime today between bloody Teams meetings.

Going off OP but throwing in a few other things to discuss or exchange thoughts on, we are focussing on harmonics and (possible) the tools to adjust but where do the other metrics associated with 22rf fit into all this, can we just look at one thing?

You have bloop tubes (still air or just sight radius?), clamped barrels with cone breaches to allow you to rotate the barrel to find a sweet spot, mechanical barrel pre stress (e.g. the Freeland stock for a 52E), twist rate (standard 1:16 dates from the horse and buggy era), number of grooves (think current BR record holder used a 2 groove after experimenting) or just plain old bedding (free float, part and full barrel).

Agree with that Terry. The whole area of .22lr accuracy is intriguing, it certainly seems more art than science. Chamber and leade angles seem very important. Correct ignition and bolt lock-up seem very important. Careful slugging of the barrel and cutting/crowning at the tightest point seems very important. 
Most successful rimfire benchrest rifles have 20-24" barrels. If shorter barrels were capable of giving the same accuracy I'm sure they would use them. Where class weight limits are concerned, chopping a few inches off the barrel and adding the to a better scope, stock etc. would be an obvious choice if there was no difference in accuracy.  I understand that the theory is that a longer barrel gives the bullet time to "relax", it's no longer accelerating and just coasts for the last few inches - maybe with less muzzle blast on the base of the bullet as it leaves the muzzle. Maybe an "air stripper" muzzle brake device would work well.

 

[brown dog]

I'm a bit horse-not-zebras.... if any of those things definitely always had and effect, that's how all guns would now be made.... most of them are voodoo and feelings in people's water rather than supported by hard repeatable data.

Have to say, the resonant-doughnut idea chimes with me, as I've often wondered why big guns - 105mm+ are so very much more accurate than small arms.... and it could go some way to explaining that... too much to type!

[terryh]

Been playing with QL to mirror some of the various data in this thread i.e.

Case capacity 3.3

Dummy cartridge configured as 22 hornet and modified Lyman lead bullet 40g

Fast powder, Unique, adjusted to give the muzzle velocities vs barrel lengths quoted.

Thus starting with the 16.25" barrel and MV of 1016 etc.:

BD

as to the horses vs zebras, I'm open to possibilities, what I have learnt is something might be right/good/real others need to be viewed with a slight jaundiced eye, the 'if it was good that's how all guns would be made' -  non sequitur, we know bedding and a good trigger is effective in improving things - but not all rifles have them because like everything improvements come with a price 😉

 

 

 

[Popsbengo]

1 hour ago, terryh said:

Been playing with QL to mirror some of the various data in this thread i.e.

Case capacity 3.3

Dummy cartridge configured as 22 hornet and modified Lyman lead bullet 40g

Fast powder, Unique, adjusted to give the muzzle velocities vs barrel lengths quoted.

Thus starting with the 16.25" barrel and MV of 1016 etc.:

BD

as to the horses vs zebras, I'm open to possibilities, what I have learnt is something might be right/good/real others need to be viewed with a slight jaundiced eye, the 'if it was good that's how all guns would be made' -  non sequitur, we know bedding and a good trigger is effective in improving things - but not all rifles have them because like everything improvements come with a price 

 

This is sort of what I did but using GK's calculator.  Your first plot is similar to my 'synthetic' and seems to be supporting the approx 1.5mS barrel time in 16". 

BD, I think your assumption of constant acceleration does not stand up,  therefor taking 50% of MV as an average velocity is also not correct.  The bulk of the acceleration is clearly in the first inch or so.

What I do agree is that so many of these ideas for improving accuracy suffer from confirmation bias,  if we expect improvements and see some we naturally assume it's due to what we just changed.  Fine in obvious step improvements but not when it's just marginal  - there's too many variables not least the nut behind the trigger

[1066]

This is taken from Varmint Al's data showing .22lr peak pressure.

[Popsbengo]

Just an idea but has anyone tried stiffening the barrel by using triangulated or 'boxed' rods/stays ?  It must have been done.

[1066]

The classic bimetal strip I would think leading to vertical stringing. A tube shroud might be better.

[brown dog]

1 hour ago, Popsbengo said:

 

BD, I think your assumption of linear acceleration does not stand up,  therefor taking 50% of MV as an average velocity is also not correct.  The bulk of the acceleration is clearly in the first inch or so.

 

I said interpolated to linear in first 16... not the whole way ..😉😊

As regards a baseline commonsense check; I mentioned earlier, even if there was no acceleration, and the bullet did the whole barrel at 324m/s  ...it would take 1.28mS to transit a 16" barrel.... so, we know any value below or near 1.28mS is patently nonsense. 😊 ...so I don't think QL looks to be producing anything 'likely to be right' for us in rimfire

Allan's cut barrel data will allow a 3-step iteration calculation... I'll do it in a mo (for a break! 😂)  I also note the barrel times shown on the X axis of the Varmint Al graph - which chime with my calculation

[Popsbengo]

5 minutes ago, 1066 said:

The classic bimetal strip I would think leading to vertical stringing. A tube shroud might be better.

Ah-ha!  But what about using clock pendulum technology - ie different metals in a cunning arrangement to balance out expansion?  Or carbon fibre.  Or a tube.  Oh, yes you thought of that

😁

[1066]

Need old John Harrison to comment here - He knew a thing or two about thermal expansion.

[Popsbengo]

1 minute ago, brown dog said:

I said interpolated to linear in first 16... not the whole way ..😉😊

As regards a baseline commonsense check; I mentioned earlier, even if there was no acceleration, and the bullet did the whole barrel at 324m/s  ...it would take 1.28mS to transit a 16" barrel.... so, we know any value below or near 1.28mS is patently nonsense. 😊 ...so I don't think QL looks to be producing anything 'likely to be right' for us in rimfire

Allan's cut barrel data will allow a 3-step iteration calculation... I'll do it in a mo (for a break! 😂)  I also note the barrel times shown on the X axis of the Varmint Al grap

As we don't know the Varmint AI barrel length it's not possible to interpolate  - could be 24"

[Popsbengo]

My quick and dirty plot of 1066's figures.

I've assumed 50% velocity in each stage as the basis for calculating - clearly that's crude but my calculation shows a barrel time of 1.79mS over 16.25"

That's going to be a smaller actual as acceleration especially in the first 3.27" is much greater - but still a small number.   Real-world 1.5mS for 16" looks reasonable to me.

[brown dog]

Right, well, here's a 4-step calculation for 16" using one of the step MVs Allan gave earlier.

Spoiler: The answer is 1.84mS

[brown dog]

Damn. Was it 16.25, not 16... standby

[Popsbengo]

2 minutes ago, brown dog said:

Damn. Was it 16.25, not 16... standby

Standing By !

[brown dog]

Answer: 1.88mS

[Popsbengo]

17 minutes ago, brown dog said:

Answer: 1.88mS

Quite a bit different to your original guesstimate of 2.5mS for 16".

I've drawn a more representative curve and recalculated = 1.57mS ± some beans

We need 1066 to chop the barrel at 1.5 " 😂

[terryh]

'.........there's too many variables not least the nut behind the trigger'

This is my limiting factor 😉