The search for the perfect barrel, and internal ballistics...

[Anthony Laversa]

Ok, so I have spent some time researching the ballistic characteristics of the 22LR. I am interested mostly in internal ballistics at this point. I started with some reading on "accuracy" as it relates to velocity and I have come up with an interesting idea I would like to bounce off the community...

We know that a 22LR bullet travelling through the the transonic zone, all the way down to Mach 0.85, can become destablized because of the turbulant nature of transioning from super-sonic to sub-sonic speeds. I have now found many instances of people online, and here on the forums, who described experiencing a reduction in group size, when they switched to "sub-sonic" rounds for shooting at "extended ranges" with 22LR. That tells me that if we can get the bullet to leave the muzzel at any speed less than Mach 0.85, 956.528871 fps it could avoid the turbulant transsonic zone entirely. <<<--- SIDE NOTE: we may be able to go a little faster since the bullet does not fully stablize until it has travelled X yards (20?) downrange anyway.

Now, switching gears, I have also heard that there can be dimminishing returns on measured fps at the muzzle as it relates to barrell length. In other words, some people have made the claim that if the barrel is too long the bullet will start to experience a reduction in muzzell velocity due to to forces of friction and as I understand it that is because the powder burn can end before the projectile reaches the muzzel. I know studies have been done on the force of friction experienced by a 5.56 NATO round as it travels down the barrel, but have never seen one for 22LR.

The other related phenomona I have read about is how the hot gasses effect a bullet travelling down a short barrel vs. a long one. Think cold bore shots, warm barrel shots, rate of fire, etc. Some information I have found insinuates that the gasses can cool down more rapidly in a longer barrel due to the increased surface area of the longer bore. Competitive shooters often use barrell lengths upwords of 24" and I believe there must be some very quanititative reasons why, perhaps this is one of them?

What I would like to do is calculate those fps losses due to friction as it relates to barrel length. However, the end goal is a little more "outside the box".

Once I can quantify the real time accelleration of a 22LR during its life in the barrel I could theoreticaly calculate the ideal twist rate per inch of travel...that would allow me to have a "gain twist rifling" profile that catered to the speed of an average 22LR at any given point in the barrell since that is a dynamic value...

I believe answering the above question(s), and creating such a barrel could ensure that,

A) An ideal barrell length, in terms of muzzel velocity & long range precision, could be quantified.
B) An ideal barrell contour, in terms of heat dissapation (for your average rate of fire), and general harmonics, could be quantified.
C) The bullet could be more gently eased into its rotation to avoid any unnessesary additional bullet defformation - which is a big deal for such a small round.
D) The spin rate itself could be optimized to increase bullet stability (after it exits the barrel).

THOUGHTS?

 

[justin amateur]

Supersonic transition and the lowly 22lr turns out to have nothing to do with loss of accuracy.
The transonic zone is from 1340 fps down to 890 fps. So almost all 22lr is running in the area of transition.
What does cause the lack of accuracy with hi-v 22lr is poor quality cartridges.
All you have to do is look at them to see problems created during the manufacture,
or use a ballistic chronograph to measure the differences in muzzle velocities due to powder/primer variations.

No rifle can "magically" fix cartridge defects. Crappy ammunition produces crappy results.
Blaming poor accuracy on transition with what is visibly second rate ammo, is a lack of comprehension of basic ballistics.

Do you see the problems?
Do you really expect repeatable trajectories?

 

[Asared]

I wonder how the new range of ammunition coming later in the year from RWS will fare out? It's categorised in their "Premium Line" of ammunition alongside Special Match, R50 and R100. It could be the first attempt at "top tier" supersonic ammo. If nothing else it'll be interesting to read about people's experiences with it.

https://rws-ammunition.com/en/infot...-2022-new-rimfire-cartridge-r-plus-long-range

 

[Anthony Laversa]

Supersonic transition and the lowly 22lr turns out to have nothing to do with loss of accuracy.

***** According to a number of notable ballisticians and a report written by the US military when they tested .22 cal bullets the above statement is not accurate, period. However, I am happy to acknowledge the fact that lack of uniformity in our ammunition is playing a roll.

The transonic zone is from 1340 fps down to 890 fps. So almost all 22lr is running in the area of transition.

***** Depending on your barrel length, ammo, and average target distances your MV could be tuned to help your projectile by reducing the time spent in that zone.

What does cause the lack of accuracy with hi-v 22lr is poor quality cartridges.

***** Agreed in my first statement

All you have to do is look at them to see problems created during the manufacture,
or use a ballistic chronograph to measure the differences in muzzle velocities due to powder/primer variations.

No rifle can "magically" fix cartridge defects. Crappy ammunition produces crappy results.
Blaming poor accuracy on transition with what is visibly second rate ammo, is a lack of comprehension of basic ballistics.

***** My father was a pilot who designed aircraft - I grew up being fed fluid dynamics concepts for breakfast. You probably should not assume or insinuate I have a “lack of comprehension” when it comes to anything related to an object passing through air at high rates of speed. Also, it is bad manners no matter who you are to insult/troll an OP.

Do you see the problems?
Do you really expect repeatable trajectories?

***** Yes! I see them, I hold them in my hands regularly - that does not stop me from pursuing repeatable results and if your not into chasing that goal why are you commenting on my thread? Please leave. I look forward to some more productive responses and if my ideas are to be critiqued maybe they could be addressed with more tact than you had.

 

[justin amateur]

Tact? Not my forte Tony.
You asked for thoughts, always dangerous here at the 'hide...you might hear something you dislike.

Do you have a copy of McCoys report on 22lr match ballistics?
Conclusion 5....with the 22lr, the transition has "insignificant" effect on accuracy.
That was the Aberdeen Ballistics lab, not my words.

https://apps.dtic.mil/dtic/tr/fulltext/u2/a229713.pdf

"5. The nonlinear Magnus moment acting on caliber .22 match bullets at transonic and
subsonic speeds causes a slow-arm limit cycle yaw of approximately 1.8 degrees. The
slow arm grows to the limit cycle value at about 50 metres range, and the limit cycle
persists out to 100 metres range. The limit cycle yaw adds approximately 2 percent
to the zero-yaw drag, but has an insignificant effect on accuracy, retained velocity and
wind sensitivity."

If you want to test hi-v ammunition, you can't start with poorly made cartridges
and expect to have meaningful results. Not when your initial premise is based on faulty data.
Interestingly enough, when you do find well made hi-v 22lr, the results show the same accuracy as match quality 22lr.
I have the data to show if you'd like.


If the transition makes hi-v 22lr produce sloppy trajectories
then how would Australian made Winchester Power Points produce a group like this at 200 yards?

Compare to Eley Tenex Biathlon

Or Eley Match

and CenterX

50 shot groups at 200 yards....those are decent sample sizes.
not y'er typical 5 shot random acts of accuracy.
If the ammo quality is good, the transition has "insignificant" effect on accuracy.


Tony....y'er thoughts?

 

[Lastsaint21]

I have made a bunch of post on snipershide about RWS100...In my Vudoo is outshoots anything else I have tried so far..It shoots 1150 fps plus. I was worried when I got it that the transition zone would mess it up..hasn't been an issue so far...what I do hate is how damn expensive it is..I lot tested 5 lots and it all shot good from 50 100 200 and 300..It was literally a toss up which lot I chose so, I simply went off SD's/ES's as the paper didn't show much difference. My hit ratio's have went up on the long distance targets at matches too.. Went 7 of 10 at 400 on a 12''x18'' 3 weeks ago and went 5/10 this weekend. This weekend was more about me taking to long to get a wind call..anyway, nothing wrong at all with RWS100..I do believe it has everything to do with Manufacturing and less to do with HV..

 

[spamassassin]

Holy overthinking it, Batman! Match ammo, 1050-1080fps. If it's stable out of the muzzle, it'll stay that way. What you're being told by people that actually do this stuff is you're overthinking it. Perhaps just accept that and move on.

 

[littlesister]

Ok, so I have spent some time researching the ballistic characteristics of the 22LR. I am interested mostly in internal ballistics at this point. I started with some reading on "accuracy" as it relates to velocity and I have come up with an interesting idea I would like to bounce off the community...

We know that a 22LR bullet travelling through the the transonic zone, all the way down to Mach 0.85, can become destablized because of the turbulant nature of transioning from super-sonic to sub-sonic speeds. I have now found many instances of people online, and here on the forums, who described experiencing a reduction in group size, when they switched to "sub-sonic" rounds for shooting at "extended ranges" with 22LR. That tells me that if we can get the bullet to leave the muzzel at any speed less than Mach 0.85, 956.528871 fps it could avoid the turbulant transsonic zone entirely. <<<--- SIDE NOTE: we may be able to go a little faster since the bullet does not fully stablize until it has travelled X yards (20?) downrange anyway.

Now, switching gears, I have also heard that there can be dimminishing returns on measured fps at the muzzle as it relates to barrell length. In other words, some people have made the claim that if the barrel is too long the bullet will start to experience a reduction in muzzell velocity due to to forces of friction and as I understand it that is because the powder burn can end before the projectile reaches the muzzel. I know studies have been done on the force of friction experienced by a 5.56 NATO round as it travels down the barrel, but have never seen one for 22LR.

The other related phenomona I have read about is how the hot gasses effect a bullet travelling down a short barrel vs. a long one. Think cold bore shots, warm barrel shots, rate of fire, etc. Some information I have found insinuates that the gasses can cool down more rapidly in a longer barrel due to the increased surface area of the longer bore. Competitive shooters often use barrell lengths upwords of 24" and I believe there must be some very quanititative reasons why, perhaps this is one of them?

What I would like to do is calculate those fps losses due to friction as it relates to barrel length. However, the end goal is a little more "outside the box".

Once I can quantify the real time accelleration of a 22LR during its life in the barrel I could theoreticaly calculate the ideal twist rate per inch of travel...that would allow me to have a "gain twist rifling" profile that catered to the speed of an average 22LR at any given point in the barrell since that is a dynamic value...

I believe answering the above question(s), and creating such a barrel could ensure that,

A) An ideal barrell length, in terms of muzzel velocity & long range precision, could be quantified.
B) An ideal barrell contour, in terms of heat dissapation (for your average rate of fire), and general harmonics, could be quantified.
C) The bullet could be more gently eased into its rotation to avoid any unnessesary additional bullet defformation - which is a big deal for such a small round.
D) The spin rate itself could be optimized to increase bullet stability (after it exits the barrel).

THOUGHTS?

The level of remfire accuracy we have today can be contributed to 50yd/m benchrest. There have been some really great and innovated Remfire smiths over the years and still are. Their sole purpose was and is to create the most accurate gun that could be built. They have tried every barrel length every twist rate every stock every action every rest you name it. It probably has been tried for 50yd competition. Here comes the long range shooters trying to reinvent the wheel and shoot a cartridge that was never designed to be accurate much past 50 yds! There will never be any consistent long range accuracy with a 22lr as long as we shoot the current ammo that is available!

 

[chevy_man]

Ok, so I have spent some time researching the ballistic characteristics of the 22LR. I am interested mostly in internal ballistics at this point. I started with some reading on "accuracy" as it relates to velocity and I have come up with an interesting idea I would like to bounce off the community...

We know that a 22LR bullet travelling through the the transonic zone, all the way down to Mach 0.85, can become destablized because of the turbulant nature of transioning from super-sonic to sub-sonic speeds. I have now found many instances of people online, and here on the forums, who described experiencing a reduction in group size, when they switched to "sub-sonic" rounds for shooting at "extended ranges" with 22LR. That tells me that if we can get the bullet to leave the muzzel at any speed less than Mach 0.85, 956.528871 fps it could avoid the turbulant transsonic zone entirely. <<<--- SIDE NOTE: we may be able to go a little faster since the bullet does not fully stablize until it has travelled X yards (20?) downrange anyway.

Now, switching gears, I have also heard that there can be dimminishing returns on measured fps at the muzzle as it relates to barrell length. In other words, some people have made the claim that if the barrel is too long the bullet will start to experience a reduction in muzzell velocity due to to forces of friction and as I understand it that is because the powder burn can end before the projectile reaches the muzzel. I know studies have been done on the force of friction experienced by a 5.56 NATO round as it travels down the barrel, but have never seen one for 22LR.

The other related phenomona I have read about is how the hot gasses effect a bullet travelling down a short barrel vs. a long one. Think cold bore shots, warm barrel shots, rate of fire, etc. Some information I have found insinuates that the gasses can cool down more rapidly in a longer barrel due to the increased surface area of the longer bore. Competitive shooters often use barrell lengths upwords of 24" and I believe there must be some very quanititative reasons why, perhaps this is one of them?

What I would like to do is calculate those fps losses due to friction as it relates to barrel length. However, the end goal is a little more "outside the box".

Once I can quantify the real time accelleration of a 22LR during its life in the barrel I could theoreticaly calculate the ideal twist rate per inch of travel...that would allow me to have a "gain twist rifling" profile that catered to the speed of an average 22LR at any given point in the barrell since that is a dynamic value...

I believe answering the above question(s), and creating such a barrel could ensure that,

A) An ideal barrell length, in terms of muzzel velocity & long range precision, could be quantified.
B) An ideal barrell contour, in terms of heat dissapation (for your average rate of fire), and general harmonics, could be quantified.
C) The bullet could be more gently eased into its rotation to avoid any unnessesary additional bullet defformation - which is a big deal for such a small round.
D) The spin rate itself could be optimized to increase bullet stability (after it exits the barrel).

THOUGHTS?

Don't concern yourself with velocity. If you slow it down below the transonic range it makes the long range aspect pointless as you're losing too much energy.

Ideal barrel length and contour is 99% driven by what the shooter needs. Weight, length, balance.

1:16 twist is used because it works well enough without too much bullet deformation.

You're missing a big part of accuracy, which is the bore diameter and muzzle diameter.


Lilja and Sheilen among others have gain twist and ratchet twist barrels available. Call them and gain from their expertise and experience.


There is some magic that we can't fully model or measure with current tech. The only solid data is old fashioned build and test.

 

[Anthony Laversa]

This was intended to be a mental exercise in how we can play with internal ballistics to try and achieve a more accurate result. Forgive me for trying to dig deeper and explore that “stuff”.

“Overthinking it” is fun for me. Some people are just built to break stuff down and try to tinker with it…

I have read some very interesting benchrest data and I think what they do in 50yrd is pretty cool - I just have different goals.

Thanks Justin Amateur, I actually appreciate the 50 round data.

I will point out that I never ignored the effect flaws in the meplat/surface of the bullet could have on trajectory…instead I offered a few ideas on what variables we can change.

- How deformed do we make our bullet via rifling in the bore? People rave about the voodoo action because the system avoids deformation - why can’t we attempt to do the same in the barrel? If we have it start at a slow twist rate and then speed up it may avoid some additional deformation.

Spinning in a short barrel, 16”, with a standard twist, 1:16, the bullet only gets to rotate one time before it leaves the muzzle.

So, how can we get it to spin a little more and perhaps encourage it to be more stable? Well, we can lengthen the barrel, or we can change the twist rate (or both)…then, how could each of those options affect the trajectory?

I choose to ask myself this stuff because the benchrest guys I see shooting rimfire are rarely (if ever) shooting 150, 200, 300, 400+ yards with a 22LR. In fact they have probably not even tried to build a rifle to achieve such feats because it’s “not their forte” and as a result I am not confident they have bothered to explore all the avenues that a NRL22, PRS Rimefire, or 22ELR/F-class style shooter may want to explore…

So, I am asking questions, getting feedback, and trying to logic it all out.

Thanks Chevy_man, that was some good feedback. I knew about Sheilen, but not Lilja - I will shoot both an email and pick their brains on the topic.

 

[Greg Langelius *]

One word.

Polygonal.

Does it have a place in this discussion?

Moving further, how about progressive rifling?

How about combining both?

I'm just spitballing here; my own knowledge level is dismal.

I'm honestly curious about the answers to my thoughts here.

Greg

 

[obx22]

Op,
A whole lot of what you mentioned has been discussed on benchrest.com and rfc almost 2 decades ago, one can’t help but wonder if mfg. and testing would have improved.
Sticking to internal ballistics, and pondering the alterations the slug undergoes from the moment it tears free of its crimp (I’ve never seen a case that appears to have “released” the slug through expansion), and the chamber lead irons the rifling form- dragging on the lands more than the grooves initially until the rifling profile is complete on the contact surfaces (I’m betting the base isn’t 100% flat around the edge). The slug slides on its journey, pushing along particles left by the previous shot, and hopefully gliding down a tube of either consistent contact, or minimally increasingly tightening bore. Tighten the bore too much, and slug lubrication becomes an issue. Tightened a lot, and the slug will be exiting the bore both longer than it started out, and a smaller diameter thereby changing both the BC, as well as it’s stability, which implies needing a faster twist.
The optimum twist vs length ratio, if I’m interpreting the claims of others correctly, seems to be range specific. This flys in the face of many claims of linear/non-linear deviation.
One claim is a 22” long 9 twist tube is the grail for 3-400yds iirc, but I haven’t got to spin one up myself yet.
I could be proven wrong, but I believe that gain or progressive twist would cause malformation of the bearing surface of the slug, and can’t help but wonder if that would add yet another variable.
It is interesting that while H&K was rumored to release a polygon bore .22LR version of their model 270, I’ve only met owners of those bores on the model 300 (.22Mag)
On the barrel length and accuracy, I personally believe that bullet upset as the skirt exits the crown, is why your average short barrel doesn’t hang with the longer tubes. It would be interesting to develop a couple of crowns that allowed “in one the lands, and in the other the grooves,) to extend past the end slightly like a (wait for it), “crown” to have controlling contact of the slug while the gasses blast by. Might work, might be horrible, just a thought. It would of course have to be protected by a brake of some type.
Longer bore time could mean a better powder burn for more consistent velocities, but that would be a separate test for chrony and saw.
None of this means diddly if you ignore rifling style as you consider bores that swage or otherwise reshape the slug. Some types are going to be more subject to crosswind displacement than others…..
Interesting rabbit hole

 

[jps2486]

The "Perfect" barrel, huh? There are a raft of barrel makers that have produced every conceivable variation in barrel length, twist rate, bore dia., rifling type ad infinitum. All of us here will disagree or agree which manufacturer makes the best. Even if we did agree which barrel is the best, some will shoot better than others. A good part of the accuracy variation is us. Then you have the wind, ammo tolerances, yada, yada, yada. All makes for good discussion.

 

[JG26_Irish]

I don't know much on this subject but could offer a few recent observations. While adjusting the ignition system on a custom rifle with the gunmaker, we were pulling the bullets out of 22lr rounds and pouring out the powder. We would load the primered cases into the rifle and test fire them in the shop. The gunsmith was using cheap bulk Remington ammo for these tests. Once we got the action functioning well, he asked me to bring a box of the Eley Black Match ammo which had failed to fire in my rifle. We pulled 4-5 of them and tested those primed cases. I noticed a significantly louder "Bang" from the Eley primers than from the budget brand Remington. This may be a part of Eley's ability to produce better match grade ammo. The stronger primer requires less overall powder to get the same velocity since the primer makes up a larger portion of the total propellant charge and May?? be easier to meter precisely (guessing). The stronger primer also does a better, faster job of igniting the powder so that it is more likely to burn more completely in the bore of the rifle and thus in theory produce more consistent velocity. I still think a 22" bbl is slightly more accurate than a 16" tube since the shorter bbl is holding the hot gases for a shorter period of time and while it might produce near max velocity, I think a slightly longer tube is just enough to generate more consistency. Other variables like bbl diameter and harmonics affect this also and is why there may not be a definative answer to bbl length and accuracy. I have a pair of 24" rifles, and two with 22" bbls and one with an 18" bbl. They are all from different suppliers so, there are too many variances to draw any solid conclusions. Still the two which are the most accurate are the 22" bores. Another that I have with a 22.75" bbl and it will beat all of them. But it is a freak of nature.