mysteries of 22lr--part2

[stagpanther]

Technically this post isn't about shooters making their own ammunition so I suppose it could be argued that it should be put on a different forum thread, but I think it belongs here because it does have some relevance to the process of making ammunition--and I do in fact handload some 22lr.

A lot of discussion goes on among 22lr fans as to how and what makes 22lr shoot accurately and consistently--especially at longer ranges where the relatively inefficient bullet design from the BC point of view becomes more vulnerable to upset in flight.

If you watch this video on Utube follow what Gavin is saying about the different grades of Lapuau's 22lr ammunition and how he tested it from 50 to 400 yards. Basically, what he is saying is that the only difference between the two types of excellent ammunition is the lot testing consistency--it is otherwise the same ammunition using the same components made on the same equipment. This is not exceptional--most if not all the top 22lr manufacturers do the same thing and offer lot testing services for users of their premium stuff.

My take--this reflects the inherent importance of tight tolerance control in their manufacturing--partly because the components and proportions/weights are so small--and partly because the limitations of the bullet's design (most use some variation of the RA4 bullet profile with the exception maybe of Cutting Edge's CURX solids for their expensive high performance bullets/ammunition) will be dramatically reflected in the bullet's performance. Minute variations from manufacturing can result in dramatically degraded consistency; especially as the distance to target gets longer. Something to think about when spending tons of money on exotic shooting hardware and/or bashing yourself over the head trying to derive the magic formula to dope out better results at longer distances.

 

[stagpanther]

Another great article on 22lr long range ballistics. I was under the mistaken assumption that drag was the biggest influence on the stability of the 22lr projectile--whereas in reality the typical 22lr match grade projectile travels "under the radar" at subsonic speed it's drag coefficient remains constant--whereas your typical supersonic high efficiency centerfire projectile actually experiences increasing drag coefficient. Here's a startling quote taken from the link (typical subsonic match-grade 22lr projectile):

"The remaining velocity is still more than half the muzzle velocity by the time the bullet reaches 600 yards. The angles of elevation at the longest distances of up to 600 yards are nearly double what they would be in a vacuum"

What i would call the top end of the 22lr transonic transition "avoidance" barrier appears to be around 1,150 fps +/- (any speed at or below will likely not suffer any serious destabilization). My impression is that supersonics are still being developed in a search for the holy grail of reducing transition destabilization and thereby improve long distance velocity and accuracy (not that they are linked). I hear about it and see videos about it--but I still haven't seen conclusive proof that it has been done in a consistent way.

 

[stagpanther]

That elevation stuff is a humdinger--today I was out shooting but it was much windier and equipment was in the way--so I had to back off from 345 yds to a bit less than half that at 166 yds. It took me almost ten shots to figure out what to dial down enough to get on target--I couldn't believe how far I had to dial down; I think it ended up being something near 2 yards difference in elevation between 345 and 166 yds.

 

[Unclenick]

The uptick in drag due to entering the transonic range begins at around 950 fps, so all 22 LR rounds, except maybe some very slow pistol match ammo, will experience some of it. Below is the RA4 drag function measured by the BRL long ago. The graph shows the drag coefficient vs. velocity for a standard atmosphere in which the speed of sound is 1116 ft/s.

 

[stagpanther]

I think I'll need to put my labradar on some tests to see what the velocity actually is exiting the barrel--it has a bit of trouble acquiring the diminutive round without using the trigger wire (which I have). I'm guessing ammo like RWS's traveling at 1150 fps +/- is designed so that it accounts for some slowing as it exits the barrel (especially longer ones) and thereby avoids the deleterious effects of transonic transition during the bullet's flight while optimizing the velocity as much as possible. As a side note--the rather marginal difference in velocity between the R-100 and tenex shows up readily in the elevation of impacts as the distances go out past 100 yds and quite profoundly at 200 yds or more.

 

[FrankenMauser]

Interesting.
I use the Hornady 4DOF app, with the standard G1 calculator, for .22 LR. As do many other people that I shoot with frequently.
I wonder if it is lacking subsonic optimization.

All of us have found it to call for what grows from questionable to obviously too much elevation, past about 150 yd.
For example, our local precision rimfire club frequently shoots steel from 250-380 yd. At 375 yd (permanent gong), my rifles call for 64.x and 66.x MoA, respectively. But in both cases, if I dial that in, I end up holding about 6 to 7.5 MoA low, in order to get impacts. And the excess elevation holds as the range gets walked back - for myself and nearly everyone else.

Shooters in the club have used multiple chronographs to get downrange velocities, used doppler systems, or have played with BC and muzzle velocity tweaks to try to dial in their calculators - often Hornady 4DOF app, standard G1; or the Lapua app (I forget the official name).

Their "results" are all over the place and somewhat confusing to me.
For example, CCI Standard Velocity is, far and away, the most common ammunition used. Stated BC is .12. I've seen many claims that it is actually .124. But the guys tweaking and messing with the BC in their apps often end up saying that a BC of .150 to .195 is closer to optimal. One shooter says he uses .172 for CCI Std, simply because it nearly perfectly matches the trajectory of Midas+ (and that is its advertised BC).

But, as always, it depends. The guys shooting 'long range' (250-400+ yd) tend to use higher BCs, while the guys shooting shorter range tend to find lower BCs to give them better results.

Perhaps I should take all three barrel lengths out and see how initial muzzle velocity correlates to the disparity at 250-375 yd. I have 16", 18", and 22" barrels on our match rifles, and 'matching' muzzle velocities. From memory: 1,043 fps, 1,068 fps, and 1,104 fps, respectively.

The 16" has been getting some Blazer ammo in testing recently, to see if the increased MV will help it at long range (1,235 fps advertised), since it doesn't seem to show any trans-sonic issues and that scope is running out of adjustment with CCI Std. However, my chronograph doesn't want to read that bullet, from any rifle, at any distance. So I don't have a true (or approximate) MV yet.

I guess the bottom line is: .22 LR continues to be mystical; and I've got work to do....

 

[stagpanther]

I often switch types of ammo shooting at 200 yds are more--that's where the confounding nature of drop calculations come into play. I'm not even sure the velocity +/- 50 fps is going to make all that much difference in drag and stability in a subsonic--but it sure as heck seems to make a difference in bullet drop. The mere fact that the actual in air drop vs "in a vacuum" calculation is near 2x at 600 yds, and is not a constant scaling factor from muzzle to target, I'm guessing is a big reason for bullet drop variability. All I know is if I get conditions that are absolutely calm with no movement in the air--I can can get pretty predictable consistency.

 

[Rimfire5]

Unclenick,

Great chart.
I believe that the Standard Atmosphere uses 59 deg F as the temperature.
The speed of sound at 55-57 degrees is just about 1113 fps.
The speed of sound is most effected by the temperature.

At 90 degrees F, the speed of sound calculates out to be 1149.3 so the ambient temperature will have a lot to do with where the transition zone is.
From what I have read, the transition zone around the speed of sound is +/- 50 fps.

So at 1113 the range would be 1063 to 1163.
Most match ammo muzzle velocities are around 1050 to 1070 based upon the ratings published. I have chronographed a lot of 22LR match ammos and their muzzle velocities are normally slightly lower than their ratings, but that might just be a bias in my chronograph.

As you pointed out, match ammos apparently discount the impact of turbulence on the low end of the curve in choosing their MVs to fall between 1050 and 1070. In my experience, the match ammo muzzle velocity range doesn't seem to make much of a difference in group sizes at 50 yards at low temperatures down to 40 or 45 degrees.
I find the difference is almost all in the quality control used in selecting what ammo lots go in to what boxes (Eley Tenex versus Match, Lapua Midas Plus versus Center-X as an example).
Around 40 to 45 degrees temperature, regardless of ammo 'quality', I find that the number of 'drops' increase to 1 out of 5 rounds and if it gets much below 40, the number of drops increases to 2 of 5. As a result, I just don't shoot .22LRs in colder weather.

Some might conclude that the drops could be the result of the speed of sound dropping below 1100 fps at around 44 deg F., but I also suspect that the small amount of powder and the rimfire primer interaction is a lot less consistent below 45 degrees, resulting in reduced firing pressure build-up more frequently. Especially since the shots that don't drop seem to group just as well as ever. I would expect that speed of sound turbulence impact should affect almost all rounds, not just 20% of them.

Have you experienced that occurrence at low temperatures?

 

[stagpanther]

I find the difference is almost all in the quality control used in selecting what ammo lots go in to what boxes

100% agree

 

[stagpanther]

Here are the results of today's shooting; wasn't ideal I had quartering tailwind of around 6 mph or so but as usual it tended to swing back and worth between left and right cross depending on gusts. However, I generally find a tailwind component is less of an issue than a headwind one. To make things interesting I shot 5 shot groups of Norma Tac 22, tenex and RWS R-100 through both my 16" CZ and 28" CZ at 139 yards and recorded the results on labradar. Since there was only one group each in each rifle the sample field probably isn't big enough to make an over-all conclusion; though it does resemble what I generally see in other sessions. Notice velocity differences between the two barrels--especially in the tenex and R100 which are very similar in both velocity delta and SD but their delta difference being less than that of the Norma ammo. While the 16" barrel generally shot faster--the 28" barrel shot smaller SDs and group sizes.

16" barrel

28" barrel

FYI--the fps difference is less than (negative)

 

[stagpanther]

While I wasn't mostly concerned about group size, it did just so happen to emerge that all groups in 28" barrel beat all the groups out of the 16" barrel--and the R-100 beat Tac 22 and tenex in both barrels.

16" R100

28" R100

 

[stagpanther]

A note about the erratic labradar results beyond 100 yards--I'm not sure how well other chronos do; but the labradar generally drops off in accuracy beyond 100 yards--especially with small bullets, these were distance settings I had left from a previous 200 yard session with a larger centerfire cartridge.

 

[Unclenick]

Yeah, page 21 of the Labradar manual says it is only reliable for 40-60 yards with a 22.

 

[stagpanther]

Shooting at dusk this evening. All the convective movement in the air was gone--but there was still a light variable cross wind of 3 to 4 mph--and when you live on the coast a hot day that ends in a cool evening almost always means a thick fog is going to roll in.

350 yds with tenex and R100--but the tenex spread too much vertically and 3 of the shots missed the target altogether--however I can't say for sure why that was so I'm not insinuating it is inferior to the R100.

The R100 did very well, the inner top 3 shots were about .25 MOA; including the 4 th shot to the right it would have been around .85 MOA. Naturally, I had to shoot a flier way down low to ruin the group--but now I am absolutely certain I can shoot at least a 5 shot group under MOA at this distance with 22lr; it's just a matter of time before I get lucky enough with conditions.

 

[Unclenick]

I watched a YouTube review of Lapua's new Long Range and Super Long Range ammunition. The Super Long Range is just a conventional load but sorted for super consistency, and in the tests, it looked good.

 

[stagpanther]

I watched a YouTube review of Lapua's new Long Range and Super Long Range ammunition. The Super Long Range is just a conventional load but sorted for super consistency, and in the tests, it looked good.

Same video I linked in post #1. I've looked everywhere for it but can't find it--the good news is that seems to lift a bit of pressure off the RWS and Ely premium stuff--but I sure would love to try the lapua stuff. RWS also has a new "super long range" but that too seems vaporware on the US market at the moment.

 

[stagpanther]

I have noticed that often manufacturers use beeswax as a bullet lubricant; though it is hard to tell whether that is "true" organic beeswax or a synthetic petroleum-based derivative. I have used pharmaceutical-grade beeswax in encaustic paintings for many years, natural beeswax has a very low "flame off" temperature where it smokes and vaporizes (around 250 degrees +/-)--it has a distinctive oder and formaldehyde is a by-product.

 

[Unclenick]

Ah! I thought I'd followed all links. Apparently not.

Did you notice Lapua now has several centers available where they will determine what lot of which of their ammo works best in your gun? I've got one just an hour or so north of me. No idea what they charge. They take your gun out of its action and mount it in a special machine rest and systematically narrow it down to the best lot. They will then sell you ammo from that lot on site, but I'm guessing it will be full MSRP, so as not to undercut their dealers. I don't know if they have stock on the new stuff or not.

I've also wanted to try their Polar Biathlon ammo. It's the only one with a slightly different bullet shape, having a tapered shoulder, and the drag function for it shows a very, very slightly higher BC at extreme range. Not enough to matter, but since the shape is different, I thought it still may worth seeing if one or another of my chambers prefers it.

 

[stagpanther]

Ah! I thought I'd followed all links. Apparently not.

Did you notice Lapua now has several centers available where they will determine what lot of which of their ammo works best in your gun? I've got one just an hour or so north of me. No idea what they charge. They take your gun out of its action and mount it in a special machine rest and systematically narrow it down to the best lot. They will then sell you ammo from that lot on site, but I'm guessing it will be full MSRP, so as not to undercut their dealers. I don't know if they have stock on the new stuff or not.

I've also wanted to try their Polar Biathlon ammo. It's the only one with a slightly different bullet shape, having a tapered shoulder, and the drag function for it shows a very, very slightly higher BC at extreme range. Not enough to matter, but since the shape is different, I thought it still may worth seeing if one or another of my chambers prefers it.

Yes--I believe Ely and RWS do the same thing. The idea as I understand it is either you buy your own ammo and if you find a sweet spot lot number they'll try to match it for you--or you bring your rifle in and they will rigid mount it, shoot and output the results using a variety of lots they have on hand and try to find the lot # which has the best results out of your bore. I'm not sure if the service is available to "mere mortals" and I have a hunch the service is not for free. Maine isn't exactly a hot spot for competitive shooting--the nearest thing I can think of is Sig Sauer in NH. It would be great for you to post your results, especially long range stuff if you decide to go down that rabbit hole. It's very addictive.

 

[DaleA]

Did you notice Lapua now has several centers available where they will determine what lot of which of their ammo works best in your gun?

Wow. What a service. Years and years ago I competed in smallbore (saying 'smallbore' is soooooo much cooler than saying '22') matches (50 feet, indoor) and even at state and local levels I can remember several folk that would have done this had the service been available. We generally shot Remington standard velocity even though we knew Eley 10x was better ammo. We couldn't afford to practice with Eley so we shot what we practiced with. At our skill level I'm not sure the better ammo would have changed any of the results.