.223 Bullet Stability?

[baddarryl]

Hi all. I need to test some 77's and 80's and have been told they don't stabilize at 100 yards. Is this true and at what yards do they if so? Shooting out of 20 inch 1:8 twist RRA LAR15. Thanks.

[RC20]

1-8 will stabilize your bullets fine.

Just a lot of noise on the 223 as there is a lot of twist rate possibles and where it started twist wise.

They are stable out the barrel, there is some contention that some bullets settle down the further rout they get. Its not unstable as it is sort of wobble.

Various combo can be on the edge of stability, supposed the first 5.56 was there and would tumble on a hit (people not targets)

Area of discussion all its own.

[Nathan]

there is some contention that some bullets settle down the further rout they get. Its not unstable as it is sort of wobble.

This is a popular hypothesis for VLD and other heavy for caliber long range bullets.

Basically, a guy will be shooting a 300 mag with 180’s getting sub 1/2” groups at 100, but groups open up a lot at 800 yards. So then they switch to some 220gr VLD. At 100yds, it shoots worse, but at 800, it is much better. The theory is it is still wobbling like a dart.

It may, but it seems more logical that the heavier bullet is less accurate, but has a lower sd. It is also likely that the long range bullet has a more consistent BC.

[jmr40]

I think 77-80 gr bullets are on the upper end of what will work with an 8 twist barrel. But it just depends on the individual bullet. It is bullet length that determines the correct barrel twist, not necessarily the weight. Some 80 gr bullets are longer than other 80 gr bullets. Some may be stable, some may not be.

You can play around with this website to get some ideas. You can select various bullets made by Berger and get a calculation on whether or not that bullet will be stable. If using another bullet you need to know the length and BC of that bullet.


https://bergerbullets.com/twist-rate-calculator/

[baddarryl]

Let me add that the fellow who told me this said it may have been just his bullets, the rifle or some other factor. Just a hunch really. I was checking to see if there is anything to it.

Specifically I have a limited range to test ammo that will be used out to 600. I only have access to 185 and thought for simplicity just to test everything at 100. It occurred to me that I may be wasting time and ammo if test results at 100 don't reflect what is happening down range. Speaking strictly stability wise out to 600. Thank you.

[Marco Califo]

http://jbmballistics.com/ballistics/.../lengths.shtml
that site has calculators, including stability, and also, the bullet lengths for most bullets. Notice that range is not a variable you need to input. It is not relevant.
I stabilize H. 75 gr bthp in a 1:9 twist 223, just fine.
Heed the COAL with those77-80 gr. Will they fit your magazine? Or, you will be single loading each round. Almost everything you need to know can be found here:
https://thefiringline.com/forums/sho...ighlight=twist

[Old_School]

Originally Posted by baddarryl

Hi all. I need to test some 77's and 80's and have been told they don't stabilize at 100 yards. Is this true and at what yards do they if so? Shooting out of 20 inch 1:8 twist RRA LAR15. Thanks.

Who told you that? Here's some 77 gr SMKs I shot yesterday out of a 1-8 twist AR @ 100 yds. The squares are 1". Now a 1-9 may not even shoot 69 gr....depends on bbl & rifle.

Sent from my SM-G781U1 using Tapatalk

[44 AMP]

supposed the first 5.56 was there and would tumble on a hit (people not targets)

There's nothing supposed about it, they did tumble after hitting people. ALL bullets that are longer than they are wide do that. They all tip/tilt (yaw) as they pass through flesh, the difference is how much distance the bullet travels before flipping end for end (tumble) and how much of that happens before the bullet exits.

The regular .30 cal GI bullets do it, but its rarely seen or recognized, because generally, by the time they do it they have already gone all the way through.

The 55gr bullet of the 5.56mm, being short and light and small diameter, compared to the .30 cal did it sooner. Tumbled while still in the body, usually.

This was "new" as in not previously seen by the rank and file (or the medics) and was siezed on, and amplified into the stories that still exist today about how special and effective it was, primarily to give the troops more confidence in the new small bore cartridge.

Did they tumble? yes. Did that make them a magic death ray?? Not so much....

[Aguila Blanca]

Originally Posted by RC20

Various combo can be on the edge of stability, supposed the first 5.56 was there and would tumble on a hit (people not targets)

There's no "supposed" about it. That was the 55-grain M193 we used in Vietnam, which is the same 55-gram M193 you can buy today. Many people use the word "tumble" (that's what word was used in RVN) but I believe the better term is "upset." When the spire point hits a somewhat solid target, the heavy tail of the bullet has a tendency to flip tail over teakettle. If the bullet is traveling fast enough, the rotational velocity when it flips (not the annular rotation, or spin) is great enough to cause the bullet jacket to fracture along the line of the cannelure, which allows the bullet to fragment. This results in multiple wound channels. And that's why the 5.56x45 round is fairly effective against humanoid targets despite being only .22 caliber. (Yes, I know it's .223, but so is .22 WMR and .22 LR.)

All you could even know about the 5.56 / .223 round:
https://www.ar15.com/ammo-oracle/

Here's the discussion about tumbling and fragmentation:
https://www.ar15.com/ammo-oracle/ter...tml?m=terminal

[Rimfire5]

Old School,

Don't believe that a 1:9 won't stabilize a 77 grain bullet.
Actually, I didn't either until I actually tried them based upon another shooter's recommendation. Boy, way he right.
I have two 1:9 twist .223s - a CZ 527 Varmint and a Savage 12 FV.
Both shoot 77 gr SMKs and TMKs as well as anything else and the 12 FV shoots them best of all.
I don't know about other 77 gr bullets but they both shoot Sierras very accurately.

[ballisticxlr]

Rimfire5 is right. What happens when you shoot a 75-77gr bullet from a 9 twist is the BC drops quite a bit. In .223 bullets the BC is trash already so they get really bad if not sufficiently stabilized. You can see your .395bc go to .340 or even lower really fast.

I shot 75's out of a 9 twist for 2 years in competition and managed to do pretty darned well with it. People saying otherwise haven't tried or had their velocities so low that the very marginal stability you get with say, a normal load in a 16" barrel was not even achieved and they never stabilized. If that's the case, you should see keyholes even up close. If a bullet starts stable in supersonic free flight, it'll never change that while in fully supersonic flight.

For me, I found accuracy benefits in my specific gun by running my .223 75gr loads at one-hitter-quitter-brass pressure levels through a 9 twist barrel. At one point I had set the #2 score for a .223 ever at my regular club match. Dunno if that still stands... doubt it.

[Shadow9mm]

Originally Posted by jmr40

I think 77-80 gr bullets are on the upper end of what will work with an 8 twist barrel. But it just depends on the individual bullet. It is bullet length that determines the correct barrel twist, not necessarily the weight. Some 80 gr bullets are longer than other 80 gr bullets. Some may be stable, some may not be.

You can play around with this website to get some ideas. You can select various bullets made by Berger and get a calculation on whether or not that bullet will be stable. If using another bullet you need to know the length and BC of that bullet.


https://bergerbullets.com/twist-rate-calculator/

What JMR40 said. Bullet stability, as I understand it has to do with 3 primary factors, bullet length, bullet diameter, and twist rate, and velocity.

As I understand it stabilization also has to do with range. I remember a story, although not the exact details. I believe it was a 1:9 twist gun shooting 77g bulets. They flew fine out to 100yds, then started keyholding when he went further. Over distance as they lost velocity, they also lost spin, and became unstable, although they were ok out to 100.

to answer your question
77g SMK, Diameter 0.224, length 0.994, BC 0.372, twist 1:8
Hodgdon reloading is showing a best velocity of 2811 with CFE223
This is gives a stability of 1.76, comfortably stable with the berger calculator.

To directly answer your question, a 77g SMK is stable in a 1:8 is comfortably stable a long as you stay above 1750fps.

Not sure what 80g bulelt you are using, but check here for bullet lengths and plug in the data. it will tell you.
https://www.jbmballistics.com/ballis...s.shtml#Sierra

[baddarryl]

I think you guys are missing the point. All I am asking is are 100 yards adequate for load testing these larger bullets?

[Shadow9mm]

Originally Posted by baddarryl

I think you guys are missing the point. All I am asking is are 100 yards adequate for load testing these larger bullets?

I think you might be missing the point.

The issue relating to "they don't stabilize at 100yds" has to do with the bullet being stable at the muzzle but becoming unstable down range. Bullets do not become stable at or after a certain range. If they are stable at the muzzle and stay stable, generally until they go subsonic. If they are under stabilized, or marginally stabilized, you can run into issue where it would be stable at 25, 50, or 75yds, but become unstable at or after 100yds.

In short, the distance you test at does not matter, as long as your bullets are stable. If it says its stable, you should be good from muzzle until it goes subsonic 800+ yards down range and at every range in-between.

here is a good read if you want more in-depth details. It also has the formula to calculate stability on your own if you want to.

https://anarchangel.blogspot.com/200...mythology.html

[Jim Watson]

A 100 yard target will get you started but you should test at the range you mean to shoot at. Assuming you are getting bragging accuracy, 100 yards may not be enough to tell a difference in two loads with "one ragged hole." Where at midrange, 300-600 yards, the natural spread will show the difference.

When I was shooting F class, I had ready access to 600 yards and did my detail testing there. I did not get a look at 800-1000 yards until a match and it was just a matter of plugging in the comeups and hoping for the best.

[baddarryl]

Originally Posted by Jim Watson

A 100 yard target will get you started but you should test at the range you mean to shoot at. Assuming you are getting bragging accuracy, 100 yards may not be enough to tell a difference in two loads with "one ragged hole." Where at midrange, 300-600 yards, the natural spread will show the difference.

When I was shooting F class, I had ready access to 600 yards and did my detail testing there. I did not get a look at 800-1000 yards until a match and it was just a matter of plugging in the comeups and hoping for the best.

Thanks. My issue is I don't have access to that kind of distance. When I do finally shoot it will be under match conditions. I have not done it before but I am prepping for NRA XTC as well as 3x600 matches.

[Shadow9mm]

Originally Posted by Jim Watson

A 100 yard target will get you started but you should test at the range you mean to shoot at. Assuming you are getting bragging accuracy, 100 yards may not be enough to tell a difference in two loads with "one ragged hole." Where at midrange, 300-600 yards, the natural spread will show the difference.

When I was shooting F class, I had ready access to 600 yards and did my detail testing there. I did not get a look at 800-1000 yards until a match and it was just a matter of plugging in the comeups and hoping for the best.

So, just curious then. Once you start stretching the distance you are testing loads at, how do you tell the difference from bad technique or a wind gust, and your load not being optimal? Granted I am loading for an AR and a budget bolt gun, but always looking to improve my understanding and technique.

[9MMand223only]

Here is 9/10 5 round groups just using N140, at 50 yards, 75, 69 and 77.
http://www.natoreloading.com/n140/

[RC20]

There are formulas on what is stable if you really are concerned about it. Longer the barrel the more velocity and the further out its ok. But 223 at best is a 600 yard round. You want better than go to 6.5.

Where is changes is when the round goes sub sonic.

But if you are unstable, you will find a non round hole in your target.

Wind will push it but not affect the neat round hole of a stable round.

[Ifishsum]

I do think it's still useful to test at 100yds if that's what you have access to. It's not like they're going to be 6MOA @100 then magically become 2MOA @600. If you can then test them to the 185 you spoke of, all the better. Keep in mind that 3.5 MOA will clean a service rifle target with room to spare, if your group is centered.

The nice thing about HP/SVC rifle loads is that there is lots of data out there for loads that will be competitive in most 20" service rifle barrels whether 7 or 8 twist. In my experience most shooters on the line use a given bullet and powder charge weight within a grain (usually less) of each other. Even after a barrel swap, I usually find that my previously proven loads are still great.

I would suggest keeping it simple to start with and find a good load for 77s at magazine length first. You can shoot all stages with that no problem, and unless it's windy the 80+ bullets don't really have an advantage. They can be fussier about seating depth and throat erosion where the 77s generally are not. You can go a long ways in the sport shooting nothing but 77s IMO