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22LR twist rate
- Thread starter Raufoss
- Start date
This is so cool.
I haven’t noticed what ammo is being tested with these barrels? Is it standard 40gr stuff? Am I correct in think a 45gr bullet would work even better with a 1-12 or so twist at standard sub sonic velocity?
@RAVAGE88 have you tested any fast twist barrels with something like Eley Contact and the slightly heavier 42gr bullets?
I haven’t noticed what ammo is being tested with these barrels? Is it standard 40gr stuff? Am I correct in think a 45gr bullet would work even better with a 1-12 or so twist at standard sub sonic velocity?
@RAVAGE88 have you tested any fast twist barrels with something like Eley Contact and the slightly heavier 42gr bullets?
I certainly do not want to speak for Mike, so this my own opinion. But there just isn’t any ammo worth testing that is loaded with anything other than 40g bullets, the consistency just isn’t there if your not shooting a premium match ammo. But maybe I’m missing something...
I’m subscribing. I’ve been seeing interesting things with air rifles shooting slugs and various twist ratios too. Calculators are often wrong. I wish I had funding to try some ideas.. I’m also curious to hear people’s thoughts onl polygonal riffing.
I talked to Carson at Lilja the other day.. They can make a barrel with up to a 9" twist. I saw a post by someone on here that said that they had ordered one from Lilja. I'm definitely interested to see how it shoots for him.
On another note, gain twist rifling is making a comeback in the centerfire world... I wish I had the wherewithal to experiment with all of the possibilities with rimfire.
It's a pretty exciting time in the rimfire world right now!
On another note, gain twist rifling is making a comeback in the centerfire world... I wish I had the wherewithal to experiment with all of the possibilities with rimfire.
It's a pretty exciting time in the rimfire world right now!
I have one on order but won’t be here until April. Had to wait until he does a run if CZ prefits.
What Vudoo is doing and what @RAVAGE88 is doing has me more excited about shooting sports and the shooting community than ever before. My wallet is ready when Vudoo is
Thank you DRB, very much appreciated.
MB
JB, I've always appreciated how you go about dissecting things in an effort to sift through what's real vs what's thought to be real. And again, it speaks to my greater appreciation for SH Rimfire Section because you just can't bring these topics up on other forums without a lot of clickety-clack on the keyboards of those subscribing to things they've never questioned. However, it was rather cool to see a very well known Small Bore Champion go against the grain on another forum about the benefits of slugging, taper lapped button barrels, etc. So, the more we shoot and question the anecdotal information by being curious enough to test the boundaries laid in place and subscribed to for reasons no one can demonstrate through qualified data, the more we advance and overall, benefit the shooting community. It wasn't long ago that you'd get laughed at for shooting at something beyond 50 yards with a 22LR, but now, things are different and the gear has evolved.
I'll paste in your list and offer what I've experienced over the years, mostly with filter off, but to some, what I'm going to say will go against the grain as it pertains to rimfire. All of what I'll say has culminated in what are the rifles we ship everyday, but having said this, I'm still learning, so the Vudoo's will continue to push the envelope. What's most interesting about this are the number of those that told me years ago that I'd never get a 22LR to do what it's doing and no one would pay that much for a 22 rifle because, "it's just a 22!" So, again, thanks JB for being genuine and for supporting the 6X5 thread that has served as a huge data collection point that tracks the evolution of what's happening in rimfire performance.
-fast twist barrels: It wasn't long ago that no one really cared about the BC of the 40 grain projectile used by Lapua, Eley, etc., but now, Lapua publishes their BC (not sure if Eley does). This is because the community started stretching the legs of the 22LR and Lapua was the first to respond by teaming up with us prior to intro'ing the V-22 to market. They developed two custom drag curves and made it available in the Lapua and Applied Ballistics apps so we could calculate firing solutions the same way we do for centerfire. Looking at the BC and doing the math to determine how much of it we're using by way of the twist rate, it became clear that out of the available .172, only .120-ish was being used with a 16 twist barrel. Working the math backwards, the solution for using all the available BC in the 40 grain bullet was considerably faster, I was astounded and questioned whether I did it correctly....so, I did it again and came up with the same answer. So, we made a few barrels. Two barrels were fit to two different actions but not at the same time. The first barrel was 18" and ultimately, it shot like crap, which was discouraging. Digging a little deeper and creating a few models to look at angular velocity vs muzzle velocity, etc., the conclusion was the barrel needed to be longer at this particular twist rate. I chambered up a barrel finished at 22" and tested initially at 50 yards. The improvement over the 18" barrel was vast....I remember looking at the first five shot group and saying out loud, "son-of-a-bitch!" After a few more groups, I handed the rifle off to Bob (whom is a sponsored shooter and does the testing based on our specific protocol) to shoot the strings of 500 round tests. The first 500 rounds is broken down into 100, five shot groups at 50 yards. Just over 90% of the groups were beautifully round and measured just over the diameter of the bullet. Amazing....but it got better. The groups at 100 were easily half the size of average groups from a 16 twist barrel (16 twist barrel was 18"). I continued to shoot this rifle for over a year and performed a silent test in September at the NRA World Championships (teamed with Lapua for the third consecutive year). We had numerous targets, all steel plates at varying distances. I took numerous prototype rifles for the masses to shoot so I could observe third party testing without the shooters knowing what was new/different and I called wind on every target for three days in a row. The groups from the fast twist barrel at distance were amazingly small and I had to call wind differently compared to the slower twist barrels. A week later, I handed the rifle off to Daniel Horner for a longer term test, but I had enough data to make more barrels ranging from my single digit favorite up to 15 twist. Bottom line is, the fast twist barrel is an absolute superstar at 22".
-barrel length: For the most part, barrel length is aesthetic when it comes to most rifle builds these days. Chassis systems with longer forends/foretubes typically need longer barrels to look right, etc. The saving grace is, in Rimfire PRS and NRL22, this really doesn't matter with a 16 twist barrel at the distances targets are engaged. A hit is a hit and the 16 twist barrels have done an excellent job and I consider these barrels to be the de-facto standard across all shooting disciplines. Generally, I've advised many ordering Vudoo's that desire to compete in these games not go longer than 20". This is because they need to move with the rifle and get into and out of position quickly and there's a slight velocity advantage for the "hit-is-a-hit" approach to the COF. Now, when I say what I'm about to say, please don't blow our phones up to change orders because I assure you with rifles in the build que, the barrel on your build sheet is exactly what you should go with. In all the test rifles I build I use a 22" barrel that's cut and crowned without muzzle threads. The reason I do this is for consistency of data and to impose controls when comparing different barrel brands when we're asked if we'll consider using so and so barrel. If/when I tell so and so barrel maker their barrel didn't pass protocols, it's not ambiguous or contaminated with "construed conventional wisdom" that's lurked around the rimfire world for years. I also don't go longer than 22" because I see velocities fall off and I need to have clear indications of lot differences in the ammo I test. The only time I'll go longer than 22" is for very specific performance criteria dictated by Benchrest, but that's not always a given. Some barrels won't perform at the longer lengths but I've not seen the presence or lack of a choke point change that at all. Barrels are barrels, they're all different and they always will be regardless of who makes them and how they're rifled. There's more to share here, but I'll hold up here for now....
-button vs cut rifled barrels: So, this is where I've seen the most popcorn-worthy internet discussions and those believing a cut rifled barrel works for 22LR get blackballed in certain circles. "Hi, my name is Mike and I've been blackballed for believing a cut rifled barrel performs at a high level of consistency and accuracy when chambered in 22LR." And guess what....I don't care, because results are results and bs is bs. Of course, this is where I'd hear (not on SH mind you), "if you look at the national results of who's winning what in the BR world, it's always a button barrel!" And I typically hear this in all capital letters on the internet or some old guy that smells like ginger snaps spraying spittle as he speaks very loudly. I generally respond with the question, "do you ever wonder why more red cars get speeding tickets?" Very simple, there are more red cars on the road, so statistically speaking, it stands to reason that more would get pulled over. Simple math will dictate, if you have 100 shooters in a BR match and 85 of them are using button barrels, how many of each will end up in the top 10? Couple this with the belief amongst various disciplines that it's just not possible for a cut rifled barrel to perform with rimfire and you'll quickly understand why there's 85 shooters in a 100 shooter match using button rifled barrels. It really does boil down to what has been construed as conventional wisdom for a very long time.
So, let's dig into this button vs cut thing a little further but I'll do it in the form of questions....What tenon diameter do you typically see in receivers used for Benchrest? Given the starting diameter of the barrel blank, how much does the bore change while turning the tenon down to .750" with a button blank? How much does it change in a cut blank? Given what happens at the front of the chamber based on this change in bore, how many rounds does it take to clean up the anomaly in front of the chamber? Are you ever really able to clean up the anomaly? Does this condition change between cut rifled and button rifled barreling processes? What material do you see this happen most (provided it actually happens), chromoly or stainless steel? Now, taking all this into account, do you see this anomaly with a larger tenon diameter, say, 1.062? Last question: How many BR actions use a tenon diameter of 1.062? Answer these questions and you're pretty far down the road to understanding one of the reasons that it really doesn't matter when you compare apples to apples.
Taper Lapped Bore vs Non-Taper Lapped Bore: What a joke....when I've asked a few "big names" (one of whom wrote a book) why one would do this, I either never get an answer or I get the same regurgitated info commonly referred to in various circles. One of whom I've come to respect was the only one to offer an honest, arrogant free answer and it was, "I don't know." From all the testing I've done, I can't come up with a single good reason that lapping a flaw into your bore is a good idea. First, how do you control the outcome barrel to barrel? What do you do when you lap too much? How do you know you lapped too much? How do you know the lapping is concentric or some esophageal feature wasn't lapped into the bore? Post lapping, what size bore are you starting with at the breech and how does this affect chambering? If there's anyone that gives an answer to any of these questions without using very expensive equipment they're not being honest with you. Basically, taper lapping a bore is always a guess. And guess what else, I've seen terrible barrels from companies that are focused on quantities; their end result only needing to resemble a barrel, shoot really well. Not for successive shots, but surprisingly well for some number of shots before having to sit for a while before they'll do something close to the same thing again. So, how does one tightly control the outcome from one barrel to the next, one rifle to the next, etc? One simple answer that's not so simple....process control. Do the same thing the same way every time and the end result will be the same. Sounds simple enough, right? Well, it's not, hence the reason the belief that taper lapped bores make a big difference. I'll stop there....
Chambers: chambers are cool, love working on them, designing them, etc., and one of my favorite rimfire chambers is the Winchester 52D. The reason I'm not using it at Vudoo is because it was designed strictly for single shot use and while I'm ok with using it in my personal repeaters, it ain't cool if we ship a rifle that won't extract a loaded round. So, I used the 52D as the basis of the 22LR RAVAGE chamber used at Vudoo. The RAVAGE chamber is a match chamber by it's very dimensions, being only slightly longer than the 52D chamber (the 52D is the shortest/tightest of all match chambers), but where it differs is the length and angle of the lead, which is how we're able to extract and eject a loaded round but still have the bullet where it needs to be for superior accuracy. Based on a few recent discoveries, I'm working on a couple new chambers but this will take a while before I'm ready to share specific details. For the BR builds I'll be doing in the lab, I'll be using the 52D chamber while I test various barrels (Vudoo, Shilen and Muller). This is where I'll be calling on JBell for a bit of third party testing....
I appreciate the opportunity to speak without a filter about things a lot of people are passionate about. Hopefully this has helped and hopefully the responses in all caps and ginger snap laden breathe will be kept to a minimum. Although, on SH, I say this in jest, it is real elsewhere
MB
And just like that, you’ve brought me 100% into the Voodoo camp.
Mike, you truly are the Christopher Columbus the rimfire world has been waiting for to point us towards the new world of rimfire performance.
This is a very old, and very much under appreciated cartridge; even though I’d dare say probably the most used on the entire planet. The fact that it is, and yet no one has bothered to really put in the time to research it in order to wring out as much performance as present, modern technology will allow is a travesty.
Time to shake the cobwebs, rock the boat, and toss the ginger snaps in trash - I loved that line by the way... the picture in my head of the angry old timer spitting crumbs at you while shaking his liver spotted fist - LMFAO!
Please keep hammering at it brother. There are those of us out here that love and respect the little cartridge, and really appreciate what you’re doing!
@RAVAGE88,
Thanks for all the great info. I always look forward to your long info posts, such great real info.
My question,
I’m sure others will want to know, will it be possible to have a Vudoo retrofitted with one of the new fast twist barrels when available?
thanks again for the passion you are giving this!
Thanks for all the great info. I always look forward to your long info posts, such great real info.
My question,
I’m sure others will want to know, will it be possible to have a Vudoo retrofitted with one of the new fast twist barrels when available?
thanks again for the passion you are giving this!
I was just playing with the Berger twist rate calculator. I don't know how long a 22 40gr is, but using half of an 80 grainer length, 1-16 is unstable, 1-14 is marginally, 12 is just getting there. 1-9 is about 3ish with 1.5 being the frontier between stable and unstable.
If we are sticking with subsonic ammo, what is the fastest twist that a hunk of lead can take?
If we are sticking with subsonic ammo, what is the fastest twist that a hunk of lead can take?
i should have added that my 1:10 barrel blank came from Shilen.
I don’t suppose the 22” kukri I ordered last month is coming in a faster twist, by chance? ?
No sir, 16 twist....more testing is underway right now for the fast twist barrels. A baseline has been set using a 16 twist barrel and CCI Standard Velocity ammo. The point of the baseline was not to look at accuracy, so the selection of rifle and ammo isn't important. Instead, the key data point in the baseline is Time Of Flight (TOF) and how it's used to calculate BC. The interesting point is, the average BC of 10 shots is .1245....exactly what the math said the range of BC would be for a 16 twist barrel.
From here, a range of twist rates will be tested to specifically look at TOF and compare BC. The goal being, to drain as much or all of the available (published) BC. Once this has been established and we're able to focus on a specific twist rate (I believe I already know what it's going to be), we'll look at multiple rifles using the same twist rate to see how much BC differs from one rifle to the next.
I'll keep everyone posted....
MB
Just going to toss this out there for guys to ponder; 60gr sss ammo but loaded to high quality like lapua and eley top shelf quality, shot out of a 1-8 or 9 barrel...
The technology is there. We just need the right people to believe in it.
The technology is there. We just need the right people to believe in it.
Fast twist barrels are going to be the hen's teeth of 2020. So do you re-barrel a barrel that will never really wear out, or just get another action....
But at what price for ammo?
But at what price for ammo?
So the TOF would be shorter the higher the BC? (Or really TOF for a given muzzle velocity?) . The shorter the TOF, the less drag? But how does twist affect BC? At an optimum twist, there is more concentric spin and less drag?
Not to answer for @RAVAGE88 but my rudimentary understanding of gyroscopic stability as it pertains to twist rates is a marginally stable bullet won't achieve it's full BC potential because the bullet will yaw more during flight than will a fully stabilized bullet. So yes, at an optimum twist rate (fully stabilizing the bullet) there should be a more concentric spin, or less yaw, thereby creating less drag.
So reading what has been previously said in the thread, the implication is that 1:16" twist may not be fully stabilizing 22lr 40gr bullets, as evidenced by not performing to their full BC value (as published by MFR) and suffering performance at distanced greater than 50 yards.
And operating at subsonic to start and just getting slower, thus needing a faster twist for optimal stability compared to a 36 gr supersonic (faster, shorter)- along with probably little expectations past 50 yards and definitely 100 yards.
Yep, probably a new action along with a new barrel. Why not, might as nuke the site from orbit. It's the only way to be sure.
Yep, probably a new action along with a new barrel. Why not, might as nuke the site from orbit. It's the only way to be sure.
20% more lead, a little less brass and a hair more powder. The price would go up in theory. As long as it’s not obscene; it doesn’t matter much to me. Guys shooting $100 bricks of centerX already. Some $150 bricks of Midas+ or $190 bricks of Tenex. Sure it would be nice if it was $39 a brick like fgmm but that’s not the realm of where we’re at.
My concern is that you'll need a Tenex level of brass+propellant+processing to take advantage of the new bullets, and the new bullets, being lathed aren't going to be cheap. Maybe lead bullets will be good enough. That would be nice. That is why I mentioned maybe MIM processing. And there is an upper band on cost at about $0.20-0.25 where people can reload 223 or buy new. Sure, there is market for 22lr ammo in that range, but the market gets smaller and smaller. At least that how I read it.
I don’t see anything need to get away from lead. If your constrained to the 22lr case length, you need the mass for subsonic work. Copper bullets would be too light I would guess, that their sleek shape won’t be able to make it up in bc. Just a guess witout really digging into it.
So what about holding copper to a 22WMR COAL, 22LR case length, and 22LR powder charge? If you’re clever with the design of the bullet itself you could probably still keep 22LR chamber compatibility, and 22WMR magazine compatibility.
The current idea is to keep it subsonic froM the start. If you can get a good bullet to start supersonic, transition seamlessly, and continue true while subsonic then we can start to look at speak copper bullets launched as fast as we can from the little case?
Just thinking about all this, and doing a bit of blue-sky brainstorming.....
One problem with the .22 LR is that it is a heeled bullet. This creates issues with bullet seating, profile, etc. etc.
The potential for improved performance from something like a .22 magnum, which is not heeled, is substantial.
Both, however, are rimfire; not only are they not practical to reload, one cannot choose the projectile.
And long range rimfire shooting is a niche market. you'd have to get a major ammo maker on-board to get match grade
.22 magnum, especially with heavy subsonic loads.
Something similar in centerfire might be the old 22 Winchester Centerfire, last produced in 1936, or the old .22 Jet.
Either of those could push 75+ grain projectiles with better BC at subsonic speeds with little to no barrel wear....
You could also neck down the .32 Long to .22, or maybe the 32 ACP. That would be about the right volume,
I think, but there are all sorts of possibilities for wildcatting cases to drive a small 0.222 diameter 75 grain bullet to ~1050 fps.
Lyman used to make molds for a variety of cast projectiles, including the 228035 which had an as-cast weight in the mid-70 grains.
if you'd want to avoid the bore wear from gilding metal jackets, which I would, and the cost, then cast projectiles make sense.
When you start talking about cost per round in range of $25 per hundred, then I start thinking about reloading. Is this rimfire?
obviously not. But thinking about rimfires conceptually, the niche it was conceived to fill is as a small no-recoil cartridge
capable of taking small game at ranges out to perhaps 75 yards.
We have stretched that to the point where one can reliably hit small game out to 200 yards or more, with modern rifles and optics.
I've shot rimfire matches with targets out to 520 yards. If we think a bit outside the box, perhaps a resurrection of the old small
centerfire .22 is worth some consideration, especially when you think about the time and effort to screen ammo, test different lots, etc.
Just some semi-random thoughts....
With regard to all who seek the Light,
Historian
If you hunt around on google, there's quite a lot of case study on 9+ twist barrels in 22lr going back quite a few years. The 60gr rounds required it to get any decent level of performance.
Everything I've ever read suggests there isn't much lost with conventional match ammo, but not much gained either. Definitely not a new idea, though it will be fun seeing how everyone gets along with it.
Everything I've ever read suggests there isn't much lost with conventional match ammo, but not much gained either. Definitely not a new idea, though it will be fun seeing how everyone gets along with it.
The testing is going incredibly well and so far the nine twist is coming out on top. The range of twists being tested is nine through 16; I just shipped a 13 twist to Rob Leatham and he'll be posting results soon. As a matter of note, a 40 grain bullet works beautifully from a nine twist barrel as long as there are a few things taken into account. I know, "but, but, Google says...."
There's a lot of "conventional wisdom" memorialized on Google that leads some to believe there's not much to be gained here and that's fine. I'd rather develop focused data instead of being satisfied with just reading what has been done years ago by so and so and then stating it as fact on the internet.
Instead, after validating actual twist (most twist rates are not exactly as advertised), we're measuring TOF (amongst other things) to properly calculate BC from one twist to the next and the cool thing is, what we're seeing validates the math. You can easily see group sizes at distance follow what we're calculating based on TOF. We have more nine twist barrels (validated) in the works now, but please don't call the shop just yet, I'll announce when they'll be ready. I just barreled up another nine twist to send to Cutting Edge Bullets and will be sharing data with them to work this forward.
MB
Thank you for taking the time to respond! My neighbor/shooting partner and I are EAGERLY awaiting the official release.
of the available fast twist barrel makers that are out there, Have any shown any superiority? I would love to have a bartelin 9tw but not looking forward to a 6month wait. The shillen 9tw ratchet doesn't look bad. Lilja seems to have a lot of the rimfire market but i believe its the fact that they have "the" name, though i have a 20yr old lilja 6.5-06 that shoots great.
I am going to thread my CZ and make a barrel to match. Having a lathe and 13yrs experience lets me tinker!
I am going to thread my CZ and make a barrel to match. Having a lathe and 13yrs experience lets me tinker!
No problem. I haven't been as available as normal, but that'll change as we complete the ramping up required for the new magazines, magnums and coming three lug single shot.
MB
I can't speak to all of the manufacturers as I've been very selective based on the need to validate actual twist rate (otherwise the data isn't accurate) but I can say that what we received from Bartlein and our own Vudoo/Ace has been awesome. If you order a faster twist barrel, ask them to validate the twist prior to shipping.
MB
MB:
I presume you are seeing effects from the non-linear aerodynamic characteristics such as the quadratic yaw drag coefficient. And thus the muzzle velocity is not sufficient to characterize the external ballistics but also need the instantaneous velocity of rotation at the muzzle. Just what solving the 6DOF equations require as initial conditions.
For those interested the BRL publication AD-A229 723 "Aerodynamic Characteristics of Caliber .22 Long Rifle Match Ammunition" by McCoy is a good read. Or forget the theory and wait for the Vudoo V-22 with a fast twist barrel to do the lab.
Rick
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Yessir and the effect on current lead bullets is non-existent as long as the increased angular velocity is dealt with by proper barrel length. The CE Bullets still require tons of work and, at this point, there are no guarantees of success with such projectiles.
MB
For certain, all else being equal, the translational and rotational speeds of a bullet at the muzzle are a function of barrel length. So a sweet spot for barrel length, not too short, not too long.
Rick
Yessir, but not just yet. I've invested in over two years of testing, in-house and third party, but not quite ready to release specific details.
MB
So you said that the velocity seemed to drop after 22". Is that drag of the bullet over-coming the pressure built by the powder?
Please give me the why / a small crash course into this. I thought barrel length and twist rate were separate of each other. Except for changed muzzle velocity (More length -> more MV -> more rotations per minute)
NM:
You are exactly correct. The rate of rotation is determined by the twist rate and the bullet velocity at the muzzle or perhaps shortly before it. The new idea, as I understand it, is that the average/effective BC from the muzzle to the target significantly depends not only on the muzzle velocity but also on the rate of rotation from the muzzle to the target. Thus the optimal muzzle velocity is therefore not the fastest muzzle velocity but presumably the fastest muzzle velocity that gives the optimal rate of rotation at the muzzle.
The way to get the optimal combination of muzzle velocity and muzzle rate of rotation is with the twist rate in conjunction with the length of the barrel since the length of barrel is constrained by aesthetics/maneuverability/etc.
Rick
Serious physic stuff! Cool!
Now... gain twist? Is that at all involved in your study? @RAVAGE88
Thanks
Now... gain twist? Is that at all involved in your study? @RAVAGE88
Thanks
At the moment, it's not. Once there's a solid relative baseline, there will be a lot to compare the gain twist to.
MB
What relative difference is there between barrel lengths vs velocity, which would (possibly) yield different TOF to target, and as such, different BC for a given brand and projectile ?
Would brand X in a 22" faster twist perform better at 50m -> 100m, but worse at 100m -> 200m, but in a 26" to 28", increase velocity, or perhaps not increase velocity, but lower your ES / SD, thus decreasing group size in the longer game ?
Is this being investigated ? I played with this a few years back, barrel length VS velocity, but specifically ES / SD variation, which I hoped would result in better long range groupings.
Yes, I found a solid answer for my specific setup, but never bothered to try and repeat for other setups.
Would brand X in a 22" faster twist perform better at 50m -> 100m, but worse at 100m -> 200m, but in a 26" to 28", increase velocity, or perhaps not increase velocity, but lower your ES / SD, thus decreasing group size in the longer game ?
Is this being investigated ? I played with this a few years back, barrel length VS velocity, but specifically ES / SD variation, which I hoped would result in better long range groupings.
Yes, I found a solid answer for my specific setup, but never bothered to try and repeat for other setups.
Another possible variable to consider, the hardness of the lead.
In Memorandum Report BRL-MR-3877 (AD-A229 713) "AERODYNAMIC CHARACTERISTICS OF CALIBER .22 LONG RIFLE MATCH AMMUNITION" by ROBERT L. McCOY,
"Figure 22 illustrates the variation of CD0 with Mach number for the custom-loaded
Eley Type Nose projectile. For all flight Mach numbers below 0.97 (velocity below 1090 fps
at standard atmospheric conditions), the Eley Type Nose bullet shows higher drag than
the Eley Tenex and the R-50. Inspection of the shadowgraphs shown as Figures 8 and 14
indicates the reason for the observed difference. All three bullets had the nominal shape
of Figure 6 when loaded into the rifle chamber. However, the Eley Tenex and R-50 bullets
are softer alloys (Brinell Hardness Number 7.4 - 7.6) than the-alloy-used in the Eley-Type
Nose and Ultra Match bullets (Brinell Hardness Number 10). The acceleration imparted
to the bullet on firing causes the ogive to set back, or slump, and for the softer Eley Tenex
and R-50 bullets, the shoulder at the junction of the ogive and cylindrical center section is
virtually swaged out. The harder Eley Type Nose bullet suffers less deformation on firing,
and the in-flight shape is much closer to the as-loaded shape, with most of the shoulder
left intact. The shock wave standing on the ogive just upstream of the shoulder in Figure
14 is the primary cause of the higher drag coefficient for the Eley Type Nose. Figures 11
and 15 show the same relative flowfield differences between the Eley Tenex and the Elev
Type Nose designs at lower speeds. Over the Mach number range from 0.975 down to 0.80,
the Eley Type Nose bullet averages 13 percent higher drag than the Eley Tenex and RWS
R-50 bullets."
How much of the drag coefficient arises from energy dissipated in form of shock waves?
In Memorandum Report BRL-MR-3877 (AD-A229 713) "AERODYNAMIC CHARACTERISTICS OF CALIBER .22 LONG RIFLE MATCH AMMUNITION" by ROBERT L. McCOY,
"Figure 22 illustrates the variation of CD0 with Mach number for the custom-loaded
Eley Type Nose projectile. For all flight Mach numbers below 0.97 (velocity below 1090 fps
at standard atmospheric conditions), the Eley Type Nose bullet shows higher drag than
the Eley Tenex and the R-50. Inspection of the shadowgraphs shown as Figures 8 and 14
indicates the reason for the observed difference. All three bullets had the nominal shape
of Figure 6 when loaded into the rifle chamber. However, the Eley Tenex and R-50 bullets
are softer alloys (Brinell Hardness Number 7.4 - 7.6) than the-alloy-used in the Eley-Type
Nose and Ultra Match bullets (Brinell Hardness Number 10). The acceleration imparted
to the bullet on firing causes the ogive to set back, or slump, and for the softer Eley Tenex
and R-50 bullets, the shoulder at the junction of the ogive and cylindrical center section is
virtually swaged out. The harder Eley Type Nose bullet suffers less deformation on firing,
and the in-flight shape is much closer to the as-loaded shape, with most of the shoulder
left intact. The shock wave standing on the ogive just upstream of the shoulder in Figure
14 is the primary cause of the higher drag coefficient for the Eley Type Nose. Figures 11
and 15 show the same relative flowfield differences between the Eley Tenex and the Elev
Type Nose designs at lower speeds. Over the Mach number range from 0.975 down to 0.80,
the Eley Type Nose bullet averages 13 percent higher drag than the Eley Tenex and RWS
R-50 bullets."
How much of the drag coefficient arises from energy dissipated in form of shock waves?
Finally!!!! After reading there was a recent discovery that rimfire ammo designed for low temps actually works in low temps, this is a timely post. Thanks Rick!
Conducted more testing in high winds today with the fast twist alongside a 16 twist of the same finished length to compare to Figure 31.
MB
Conducted more testing in high winds today with the fast twist alongside a 16 twist of the same finished length to compare to Figure 31.
MB
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