@stagpanther, and other tech nerds!

[MarkCO]

I'll add a log to the fire. My "precision" 22rf has been shot in a variety of environmental conditions. Not enough data to be considered reliable, but it is intriguing. I found that it is, in fact, more accurate past the transonic range at 11,000 feet than it is at 1,000 feet. That got me thinking, so with the help of a friend, we increased the airflow in an indoor range with walls, baffles, louvers held open and a few more fans. The speed of air was about 20 mph. It did increase the accuracy at 50, 75 and 100 yards, but there are several theories that could explain that. The bullet was going transonic at about 20 yards. I just know that in Talledega in July, I could never get the same accuracy as I could get at 8000 feet in January.

[taylorce1]

Originally Posted by tangolima

So far the single biggest factor in long range accuracy that I have found is pretty non-technical: shoot in calm conditions.

That's why I'm hoping Litz will be able to design a more predictable model for rimfire ammunition. If he's able to build trajectory models that will give you 25%+ better hits on target beyond 100 yards. I'd call that a significant win for the community.

[tangolima]

There is substantial difference in poi, as reflected in the dope table, between HV (1200fps) and SV (1000fps). That means difference in TOF.

I shoot soda can placed on dirt berm at 150yd. There is big difference in the kicked up dust and the way the soda can jumps. That means difference in terminal energy out at 150yd.

I don't think they become the same within yards. 1200fps vs 1000fps may not seem a lot of difference, but it is still 20%.

-TL

Sent from my SM-N960U using Tapatalk

[taylorce1]

@FrankenMauser,

Thank you very much for the review! I've wanted a .17 HM2 for quite awhile now, and have been looking at .22 lr I could rebarrel to one. CZ 455, Ruger 77/22, and custom 700 SA footprint actions. All put me in or over the Volquartsen Summit price range. I also decided if I bought a custom action, I'd probably just build a .22lr.

I know that Umarex now owns Hammerli, so I'm kind of worried the quality might suffer. I've only been around Hammerli air rifles/pistols when my Daughter shot in the Olympic Training Center Youth Program.

I knew it would accept any 10/22 aftermarket trigger. I also like that it's a 10/22 footprint so you can upgrade the stock later. I just don't know why they did a barrel nut for the barrel, instead of just copying the 10/22 again?

[tangolima]

Originally Posted by MarkCO

I'll add a log to the fire. My "precision" 22rf has been shot in a variety of environmental conditions. Not enough data to be considered reliable, but it is intriguing. I found that it is, in fact, more accurate past the transonic range at 11,000 feet than it is at 1,000 feet. That got me thinking, so with the help of a friend, we increased the airflow in an indoor range with walls, baffles, louvers held open and a few more fans. The speed of air was about 20 mph. It did increase the accuracy at 50, 75 and 100 yards, but there are several theories that could explain that. The bullet was going transonic at about 20 yards. I just know that in Talledega in July, I could never get the same accuracy as I could get at 8000 feet in January.

That's interesting. High altitude and tail wind improve accuracy. First order impression is lower drag and shorter TOF.

-TL

Sent from my SM-N960U using Tapatalk

[davidsog]

Actually, the inherent stability of the predominant 22lr bullet design at slower speeds is outstanding and pretty much stays that way as velocity decays

Yep. This is a stability and control problem that has plagued aerial vehicle designers since its discovery in the 1930's.

Modern aircraft that travel in the transonic and supersonic realm have a thing called "mach trim" to help deal with it as well as some basic design characteristics for that realm of flight.

The nature of normal shock is why.

https://www.grc.nasa.gov/WWW/k-12/airplane/normal.html

Normal shock is caused by local air velocities that exceed the speed of sound. The stability and control issues are caused by the fact that immediately behind that normal shock is a local velocity reversal.

This causes the flow to seperate.



In a subsonic aircraft, that normal shock can progress over the body and put the control surfaces into that seperated portion of flow making control of the aircraft impossible. That is how compressibility was first discovered when test pilots would dive into the ground to their deaths because their control surfaces no longer functioned.

As that normal shock progresses, that flow separation acts like a vacuum and changes the relationship of the Center of Gravity and the Center of Pressure.

Mach Trim essentially represents a force reversal and moves in the opposite direction of subsonic trim. That is one reason why "The sound barrier" was thought to be an actual barrier because trim forces would reverse and pilots would applying normal trim would overload the airframe killing themselves in a dramatic cloud of debris or at best lose control damaging the aircraft.

A subsonic vehicle must have the Center of Gravity in front of the Center of Pressure to be both statically and dynamically stable.

That is how a pellet is set up in an air gun.

The supersonic realm reverses that relationship and the CG is behind the CP when the object is at rest. That is why your high power rifle bullet's CG is behind the CP and why it will tumble at low velocity. It is set up that way so that as the CP moves rearward due to normal shock formation, the CG then becomes ahead of the CP in flight to achieve stability.

Here the flight trim constraint is defined as follows: the location of CP is ahead of the most aft CG during
the cruise segment[s] for the specified flight mission requirements.

file:///C:/Users/Owner/Downloads/20160005997%20(1).pdf

The results supported the earlier trends observed by Caldwell and Fales. In particular, Briggs found:16


Lift coefficient for a fixed angle of attack decreases very rapidly as the speed increases.

The drag coefficient increases rapidly.
The center-of-pressure moves back towards the trailing edge.
The "critical speed" at which these occur decreases as the angle of attack is increased and the airfoil thickness is increased.

In 1924, the culmination of this work, as well as that which went before, was the waving of a red flag —compressibility effects were nasty and they markedly degraded airfoil performance. But nobody had any fundamental understanding of the physical features of the flow field which were causing these adverse effects. This was not to come for another decade.

https://www.nasa.gov/history/SP-4219/Chapter3.html

Since our bullet does not have a mach trim system to account for the rearward movement of the CP due to normal shock formation we can either design a bullet for subsonic flight or supersonic flight.

[FrankenMauser]

Lapua, supposedly, did a lot of work to optimize the shape of the bullet used in the Long Range and Super Long Range ammo.
However, I have not been able to find a photo or video of a bullet that someone pulled. Nor do I have any on hand to disassemble.
I'd like to see how that bullet differs from their others.

I knew it would accept any 10/22 aftermarket trigger. I also like that it's a 10/22 footprint so you can upgrade the stock later. I just don't know why they did a barrel nut for the barrel, instead of just copying the 10/22 again?

Maybe they got a discount on a bunch of air chucks.

I did not know that Umarex owns the brand now.

[stagpanther]

Since our bullet does not have a mach trim system to account for the rearward movement of the CP due to normal shock formation we can either design a bullet for subsonic flight or supersonic flight.

Main problem being designing a "launch system" (firearm) that can do either/both well within the diminutive constraints of the 22lr. I suspect it can't be done--but I certainly hope I'm wrong!

Maybe someone will develop some kind of sleeved "microsabbot" and will usher in the age of $2.00 a round 22lr.

I would have never thought a muzzleloader could shoot as well as a good centerfire cased cartridge--and then the CVA Paramount came along.

[davidsog]

Main problem being designing a "launch system" (firearm) that can do either/both well within the diminutive constraints of the 22lr. I suspect it can't be done--but I certainly hope I'm wrong!

It would be revolutionary if they did. The fact that technology has advanced to the point this can all be measured not by taxpayer funded Government but by private industry give me reason to both smile and hope.

[stagpanther]

The "critical speed" at which these occur decreases as the angle of attack is increased and the airfoil thickness is increased.

I used to fly with tufts attached along the camber of the topsurface of the wing--you can actually see the effects of this when the airflow not only breaks from the surface--but reverses direction and points to the leading edge. Delta wing gliders are nice in that they have variable twist from the root to the tip so that you get progressive stalls rather than "all at once."

[taylorce1]

@stagpanther,

We were talking about the B1 on another forum. Here is what he had to say:

They announced them a month ago and it was mentioned here that Hammerli is part of Umarex now. It may not be the same Hammerli we've come to respect.

After being burned buying a Turkish 22 with an American brand name recently, I'll wait for accuracy reviews before I buy one.

I do like the concept!

I found out later that Turkish 22 he's talking about is the Springfield 2020 rimfire.

[FrankenMauser]

I also have a Springfield 2020R. Not good out of the box. But they can be quite good with a little stock work and a Kimber 84M scope base. Barrels are good and much of the design is quite good. I have a theory on why they have developed a reputation for inconsistent performance, even when stock work is done to eliminate that part of the problem.
But some machining is required to test that theory, so it'll have to wait for now.

Maybe someone will develop some kind of sleeved "microsabbot" and will usher in the age of $2.00 a round 22lr.

Well... Have you seen the latest rimfire addition to the SAAMI cartridge list?

.21 Sharp
Seems to be .22 LR but with a solid copper bullet that is not heeled.

[stagpanther]

.21 Sharp
Seems to be .22 LR but with a solid copper bullet that is not heeled.

It looks like they are offering what has already been developed by custom barrel makers--a custom 22 barrel that is intended to have solids/jacketed engrave to the bore rather than "form-fitting" all lead/lubricated ones. I found that you really can't use the types of ammo interchangeably in the same barrel for fouling reasons so Winnie looks like they already have said this is a different bore/bullet. The bar is pretty high for them to prove this is really worthwhile compared to what else is already out there IMHO.

[MarkCO]

Originally Posted by tangolima

That's interesting. High altitude and tail wind improve accuracy. First order impression is lower drag and shorter TOF.

-TL

Sent from my SM-N960U using Tapatalk

Maybe, but less "force" from turbulence due to thinner air and mitigation of turbulence can also be an explanation. I've not taken the time to model it with CFD. I expect it is a combination of factors that may actually impact other variables.