Long Range 101 Part 67 - Bullet Stability

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11 жыл бұрын

Bullet stability is a topic that seems to have many long ranges enthusiasts chasing their tails round and round. There are a number of dynamically interrelating factors that play off of each other in various ways resulting in a bullets overall stability or instability. Whether you are using the Greenhill formula, the Miller formula, or McGryo's mathematical monster - the full story of any bullet's stability characteristics is incredibly difficult to express on paper.
Twist Rates: Determining which twist rate is most appropriate for a given bullet is the big question here. One can get a basic idea as to the predicted stability trends a particular bullet may display when fired through a certain twist, but the only way to know for sure is test it in the field. Often, bullets that should be too long and heavy for a given twist work great while other bullets that should have been easy to tame are going wild. Most manufacturers publish their recommended twist rates for their different bullet tests, so this may be a good way to go. If you don't know what twist would be best, you can try one of the formulas to get a basic estimation.
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All the music in this video was created by TiborasaurusRex, an unsigned artist.
Song Titles: Wadi Watir, Particle Jam, Magnetic Night
Music and Lyrics by: TiborasaurusRex
Instrumentation and Vocals by: TiborasaurusRex
Recorded by: TiborasaurusRex

Пікірлер: 66

@TiborasaurusRex 5 жыл бұрын

Come train with Rex!!! It would be an honor to meet you in person! rexdefense.com/

@TiborasaurusRex 11 жыл бұрын

lol Yeah, I started realizing that a while ago - I kept the designation '101' as its way too catchy. Here's the REAL sniper 101 in a nutshell: 1. Get a rifle, a LR optic, and good ammo. 2. Zero it. 3. Learn its trajectory profile and make a table. 4. Range a target and dial in the optic according with all the right corrections. 5. Get your eye perfectly behind the scope and the crosshairs on the target. 6. Squeeze trigger as to not wiggle the rifle off target. 7. Observe Impact and smile.

@TiborasaurusRex 11 жыл бұрын

Glad to hear these are helpful, sir. Thanks for watching!

@The89burban 11 жыл бұрын

I thought sniper 101 was how many vids your going to end up with. Keep it up! your doing good work! even if half of it goes right over my head.

@westleyjohn87 10 жыл бұрын

You have a great way of explaining this stuff! Even I van understand it. Thanks rex.

@TiborasaurusRex 11 жыл бұрын

Yeah, I've had similar results in the past. Its best to test it for yourself to see how well they really perform. Thanks for the report and for sharing the information with us. Peace.

@Youngsoldier93 11 жыл бұрын

Rex, I just want to thank you and to say keep up the good, detailed work! I'm loving you channel haha

@BigBUSN 11 жыл бұрын

Great videos. I've been shooting long range for 2 years now and I'm learning a lot that I didn't know.

@georgepatriarca7923 10 жыл бұрын

Brother, I have to tell you that my head spins with all the technical information you spell out in your videos..only because I am finding that all the things I thought I knew are slight misunderstandings. Thank you for sharing your knowledge and passion.

@outlander330cc 9 жыл бұрын

I'm glad I'm not the only one haha

@pukkagoblin 11 жыл бұрын

The most intelligent thing I have to say is thanks Rex. Vids are great, learning so much.

@SVtgr8 11 жыл бұрын

another good one - well done buddy

@TiborasaurusRex 10 жыл бұрын

Not necessarily, but the answer to this would of course hinge on your exact mission criteria. If hard core external ballistic performance is needed to extend your effective range or if you need to improve your terminal performance to put down a tough target effectively, then a super magnum may be warranted. Usually, a super hot load is not needed, but if you are pushing it out to the outer edge quite often, then that extra oomph is your friend for sure. Ultra magnums have their place for sure.

@carpmaster87 10 жыл бұрын

I read this with some interest, and wondered if you thought this might be one explanation for why suppressors are thought to have "some" potential increase in accuracy ? From Bryan Litz's article: - " I re-read the section in Modern Exterior Ballistics about epicyclic swerve. The part that jumped out was where the author (Bob McCoy) says that the radius of the corkscrew motion is usually less than one caliber, whereas the aerodynamic jump is many times greater, and causes dispersion that is proportional to range (linear). In other words, if the initial pitching and yawing is aggravated randomly by muzzle blast, if you get a 1.5” group at 100 yards that increases to 3.0” at 200, etc, only 0.03” of that dispersion is due to epicyclic swerve." - specifically the statement "initial pitching and yawing is aggravated randomly by muzzle blast"

@viswajeetrao1240 3 жыл бұрын

Nice

@TiborasaurusRex 11 жыл бұрын

It might, depends on your atmospheric conditions. If you are at higher altitudes, it may work very well. If not, it may or may not work. Most guys would consider that to be too slow of a twist rate for that bullet. I might be more comfortable with a 1:9" twist for that exact bullet in most conditions, but a test may warranted to find out for sure. I have gotten excellent results in the past with twist rates commonly deemed "too slow". So check it out ;-)

@colinwalls6130 11 жыл бұрын

great video as always my very intelligent friend

@kmose73 11 жыл бұрын

@ Kevin Humrighouse. Bullets stabalize more easily at higher elevation. Sierra's data is probably figured for sea level, as that would be the lowest anyone would be shooting their bullets. My guess is that you are quite a bit higher than that, hence the ability to stabalize the 77 grainers. If you were to take a little safari down to death valley you might have different results.

@braplife13 8 жыл бұрын

Excellent discusion sir! lets see that calculus for the last formula!

@W6RIPRadioAdventures 11 жыл бұрын

I have been testing the with the .223 77gr matchkings. I think manufacturers are conservatiive with recommended twist rates. When choosing the heaviest bullet my gun would stabilize, manufactures recommend nothing more than 69gr in a 9" twist. I took a risk with the 77gr. I couldn't wait for the 7mm to test what you have taught us. I am shooting sub half minute with the 77gr. and making consistent 600 yard shots.I just believed that with a 24" barrel and Copper Equilibrium that it would work;)

@saltysteel3996 7 жыл бұрын

Love the music.

@Hockeycoho 6 жыл бұрын

Put these all together on a DVD and I will buy couple !

@bagheri4 6 жыл бұрын

Which bullet weight would you recommend for 1.12 twist rate on my 270 win. For long distance shooting . Thx

@W6RIPRadioAdventures 11 жыл бұрын

2748 @ 70 deg. No sure if you saw my video on my load development but it might help. I tried a tenth above max load and it was my worst group. That MV was figured with Rex's Ammo Temp MV curve chart. See what your results are at close range with the 77s first and work up a good load for your rifle then go long. I didn't shoot for groups @ 600 but I ended up hitting 3 different swinging targets in row that were about 1ftx1ft thanks to a 12oclock wind. Keep me posted with your results. Thanks.

@temmenj100 11 жыл бұрын

Hey Rex I remember reading comments on one of your other videos and you said you had a hard time finding spotting scopes with a milliradian ranging reticle so i searched around and Vortex has a monocular for around $120 called Solo R/T 8x36 mm Tactical Monocular that has a milliradian reticle, not sure of the quality or accuracy of the marks seeing as I have not purchased one but it might be someting you might be interested in, keep up the great videos!

@mac45110 8 жыл бұрын

Rex, Having waded through the ballistics excel spreadsheets to set up for my most likely applications, I have one question regarding bullet stabilty: What is the basis for stating that the stability factor should fall between 1.4 and 2.0? I haven't found yet the calculation that would explain that statement. Shooting a .308 Match King of 168 gr, it comes up greater than a factor of 2.0 at mid to higher temps out of a 1:10 twist barrel. For a bullet with such a good reputation for accuracy, that doen't seem right. What am I missing?

@antoniogalvan8488 6 жыл бұрын

TiborasaurusRex, I recently purchased a stock Tikka T3 Lite chambered in .300 WSM for hunting/target application. The rifle has a 24in barrel with a 1/11 twist rate, I have been getting 1 inch groups at 100 yards consistently using the Hornady 180 grain SST bullets backed by 62.7 grains of IMR4350 (2836 FPS). Any suggestions on what grain of bullet/brand I should purchase to shrink those groups? Much thanks in advance-Tony

@Nyksta 11 жыл бұрын

As the bullet loses velocity over distance due to drag, does drag equally affect RPM of the spin, or does the rate of of spin remain steady all the way from muzzle to target?

@glennwih 11 жыл бұрын

Ogive? Bearing Surface? Let's talk about all the parts of the bullet.

@akshay1935 5 жыл бұрын

Which paper do you refer for stability

@vladimirabadzhiev3246 4 жыл бұрын

man that is cool but how can i change my twist if it isnt enough or if it is too much. Do you need to change the bullet ?

@Jimbojenkins 10 жыл бұрын

Harry Pope did extensive experiments on bullet stability as far as spin rates to even to extreme twists that bullets flew apart upon leaving the support of the barrel.

@sooyek78 11 жыл бұрын

"..so why not to skip the whole thing and do an actual test..." - engineer speaking - LOvE it!!!

@twwtb 7 жыл бұрын

Fore sure that's would yield the best information, but before you did the testing, you had to make a decision and order a barrel. As far as I know, there is no such thing as an adjustable twist barrel, but it would be a good invention if it could be made to work.

@TiborasaurusRex 11 жыл бұрын

lol - don't worry about it! I am theologically hybrid anyways, it would be very hard to pin me down on which exact flavor I am.

@beas302 9 жыл бұрын

Do you think that 11 degree muzzle crowns have a destabilizing effect on the bullet leaving the barrel? It seems like the crown would act like a lens focusing the shock wave,caused by the expanding powder, onto the bullet destabilizing it slightly during initial phase of flight causing a decrease in accuracy. Do you think a reverse muzzle crown would have the effect of releaving the shock wave away from the bullet allowing for increased accuracy?

@oscarbear7498 Жыл бұрын

Her: " where are all the good men at?😭" Loyal man: "so if you look at the center of pressure, you can see its at a distance from the center of gravity🤓 "

@pasky2112 11 жыл бұрын

Ha! I'm doing the exact same tests. What's you're MV? I have a 20" 1:9" on an AR that easily shoots 1 MOA @ 300y w/ the 69g SMK's at ~2900fps. But I get 7-8 ring shots at 600yds. w/ mostly lateral dispersion. Hence, testing the 77's which, as u know, advert. 1:8 or faster twists. Like Rex sugg, I want to c 4 myself but haven't been to 600y range, yet. I'd have to load hot to get 2900fps out a 20" for a 77g. Just curious what yours is at. Thx.

@SmithAerosports1 11 жыл бұрын

Cool....

@BigBUSN 11 жыл бұрын

I have no problem hitting targets out to 1000yards or so. But it's nice to know why the bullet is doing the things it's doing.

@saigudbai 6 жыл бұрын

I'm starting to really see there are a lot of trade offs to make. Trying to build a heavy for caliber load for 30-06. I'm either getting fantastic BC's with ELD-X and 200 or 178 grain but lower stability calculations, or I'm getting fantastic stability numbers from 220 grain Nosler Partition with lower BC's and less retained energy as the distance goes further. Decisions, decisions. I feel it's going to come down to the most likely range I'm going to be hunting (closer), and the great terminal performance of a heavy bullet on large game.

@saigudbai 6 жыл бұрын

Thanks for that info. lowest stability I calculated was 1.33 with the 200 grain ELD-X and my 11 twist Tikka, but I won't likely shoot past 250 meters.

@captainpegs0740 9 жыл бұрын

I bought a new Handi rifle in the heavy barrel varmint configuration as an experiment to see if all the hoop-la about their accuracy was true. It has 1/9 twist and I'm shocked how accurate it is, even with the crappy trigger. This got me thinking of re-chambering: If I'm shooting a 70 Berger in the 223 and re-chamber the gun to 220 swift, could I run into a problem of having too much twist, with 220 Swift velocities, where I start shedding jacket and key-holing? What if a person tried a 22 Middlestead with the 1/9?

@glennwih 11 жыл бұрын

I disagree with your statement at 15:30 about concentricity. Only a cold swaged bullet is uniform. Hot swaged is too but less then solid billet milled bullets.

@Ducky27645 9 жыл бұрын

Hey Rex, you made a statement that I'm trying to figure out. "That's some of the reason it's harder to stable some of the AP bullets" @ 14:50. I realize lead is more dense than steel, however there are a variety of steel densities. Harder density steels are used which gives AP rounds the density needed to punch through armor. With this steel being this dense (and heavier due to density,) why are they harder to stabilize?

@TiborasaurusRex 9 жыл бұрын

Ducky27645 Its a concentricity issue due to quality of construction on these AP bullets which is usually not up to the same level of precision as standard target or hunting bullets. Not so much a density issue but a quality of manufacture issue.

@glennwih 11 жыл бұрын

BRASS-Breath, Relax, Aim, Stop, Squeeze

@defibaughjd7 11 жыл бұрын

I don't mean to nitpick, bro, but some of these topics are at least Sniper 201, maybe even Sniper 301 level topics. ;) haha, jk. Thanks for sharing these...a lot of good information, even for experienced shooters.

@lordjor96 8 жыл бұрын

what afect a bullet by adding or removing groooves from a rifle

@HarrisonCountyStudio 4 жыл бұрын

“groooves” ? I believe you meant rifling... the rifling gives a twist to the projectile. Generally speaking, the higher the twist or spin rate (adding grooves) the faster the bullet will turn. There are optimum twist rates for specific calibers and weight/length of the projectile. Rex is a wealth of info. Keep watching his content, and you will learn more than you could have ever believed to learn from a video.

@NachoMenegazzo 10 жыл бұрын

Hi! i have a 243 Ackley, i run Mostly Hornady 105gr Match (.450" bearing surface and .530 BC) in a 1-8tw 28" Krieger. Im planing to get some Bergers and Lapua Scennars "L" and my question is.... Hybrid or VLD? for short range 200yrds and 300yrds Matches and Long Range Performance with RL25 and CCI 200

@pzkw108 10 жыл бұрын

"short range 200yrds and 300yrds Matches and Long Range Performance" that's a wide variety of application ???

@kn761 7 жыл бұрын

what relevance is the bearing surface?

@pukkagoblin 11 жыл бұрын

Dearly, there's an Australian mob that make 1" .338&.416 slug. It looks basically like a piece of dowel. Just a solid brass slug. The nose has an inverted dome, almost a scoop! It looks wrong, and shoots like a tac. Woodleigh bullets.

@debasispanda7579 6 жыл бұрын

Can I contact you.... I'm doing a project on field gun shell... At Indian institute of technology....

@W6RIPRadioAdventures 11 жыл бұрын

Probably. I was at 1500 ft.

@kmose73 11 жыл бұрын

stabilize. Sorry i mispelled that in my post!

@glennwih 11 жыл бұрын

Did you know that a 2lb trigger pull is more accurate than a 1lb?

@tyronekim3506 5 жыл бұрын

You're throwing a lot of technical words like center of gravity, center of pressure, moment of inertia, dynamic stability, etc., but not explaining how those things effect stability.