As someone who never had a dad or grandpa teach me about firearms or the likes I really apperciate this videos. Keep up the good work!
@sdkweber3 ай бұрын
Thank you very much. I truly hope you are enjoying these videos and learning some things about our sport.
@trevorkolmatycki40423 ай бұрын
You do a fine job of explaining this topic sir. Any imperfections in the bullet that affects the radial balance of the bullet IE looking at the bullet in cross section if the center of the bullet and the center of mass are not aligned due to variation in jacket thickness or variation in lead density or presence of porosity etc… this slight radial imbalance causes the precession cycles of the nose of the bullet to become enhanced or increased. Radial imbalances cause the spinning bullet to be perturbed and this perturbance is greater the faster it spins which increases dispersion. Modern premium bullet manufacturing has improved such that bullets are more dimensionally precise with less of this radial imbalance than bullets manufactured decades ago. So with cup and core bullets it is best to avoid over spinning bullets especially if you are running mass produced lower cost bullets that aren’t as dimensionally precise. Elite ELR shooters even use bullets precisely machined from monolithic materials to try to achieve perfect radial geometry so they can capitalize on fast twist with very long bullets without incurring increased dispersion due to these effects… and whatever other magic they embark upon to deal with dynamic stability in the transonic and subsonic zones that I do not fully understand. Projectile stability is a very interesting topic. Cheers!
@sdkweber3 ай бұрын
This is some very good extra information. Thank you for posting this! Well done.
@PJ_Perry3 ай бұрын
The 8 blk out with 1:1 twist rate is crazy i wonder if other calibers would benifit from that...but gems of knowledge dropped in this video
@stephenarmstrong73543 ай бұрын
You might enjoy James A Boatright's paper, Hyper-stablized rifle bullets. He also has another paper, Bullet Obturation. Thanks for the video.
@michaelarthur50263 ай бұрын
Love this guy
@blackhawk7r2213 ай бұрын
When you get a puff of grey cloud twenty feet from your muzzle, you’re over spinning. Yea. Seen it.
@charliegrandison11763 ай бұрын
Wow! That was an awesome video! Thank you.
@sdkweber3 ай бұрын
Glad you liked it! Thanks for watching and posting.
@donwyoming19363 ай бұрын
A full power 5.56X45 round in a 1-7 twist is rotating at over 200,000 RPM. If you've ever loaded light 45-55gr varmint soft points, fired from a 20-24" 1-7 barrel, the projectiles will often self-destruct just a few feet from the muzzle. It was a real problem for me in the 80s & 90s (as noted in the Speer reloading manuals). By 2000, it seemed the 55gr soft points were not so thin skinned. They could survive full power loads in a 1-7 now.
@russr3 ай бұрын
thats not over stabilized... thats just exceeding it construction.
@sdkweber3 ай бұрын
@@russr Correct. Over-spun but not over stabilized. I shot 40 grain varmint bullets in my .220 Swift at 4,230 fps and some of those just vaporized between me and the target.
@sprky7773 ай бұрын
A bullet is like a flywheel. It takes energy to spin it. It dissipates that energy into the target. Overspinning a projectile diverts energy from velocity into rotation. It should be spun enough to stabilize but not much more than necessary.
@russr3 ай бұрын
@@sdkweber yeah, I had some Sierra 50 grain soft points play kept exploding about 10 ft out of the muzzle in my AR.. I never really had problems with VMAX. I had a load for my 40 grain V-Max what's 28 grains of 748 which is a compressed load and it would shoot under a half inch of 200 yd.... 223 load
@sdkweber3 ай бұрын
@@russr I have used a lot of moly coated VMAX bullets in my .220 Swift and I like the Winchester/Nosler Combined Technology 40gr. bullets. That VMAX was shooting well for you. I hope you stocked up on those bullets. :)
@driverjamescopeland3 ай бұрын
I'm glad someone FINALLY decided to make a video on this. Putting a 1/3 twist barrel on your grandpa's 30-30 isn't going to magically give it match-grade performance. Bullet profile and consistency have more to do with accuracy than over-stock twist rate. Also, there are a lot of "match grade" bullets out there, that simply aren't. People think those words automatically translate to better accuracy... when it could simply be a specified profile/weight of any sanctioning body. Back in the old days of shotgun slug matches, some rules actually dictated real slugs... as in, what closely resembles a piece of bar stock with a round nose.
@sdkweber3 ай бұрын
Well said James. Thanks for watching and posting.
@driverjamescopeland3 ай бұрын
@@sdkweber - thanks again, for the content. 👍
@mikesauer77753 ай бұрын
I reloaded some blem 2nds. 40gr V-max look alike with blue tip. I suspect they were 5.7x28 bullets as my.223 1 in 8 twist rifle doing 3700fps spit a shard of jacket into my chronograph display. Over spun at speed? My 24"W.O.A.1-12 twist spits them out at 3850fps with great results
@russr3 ай бұрын
thats not over stabilized... thats just exceeding it construction.
@jasonshults3683 ай бұрын
There are a lot of factors that can cause a bullet to come apart after leaving the muzzle. Among the most significant is the condition of the bore.
@OldManMontgomery3 ай бұрын
In my experience, 'a little too much' overspin is better in results than 'a little' underspin. In .308 caliber, the 1903 Springfield was designed for 220 grain round nosed bullets initially, but quickly changed to a somewhat faster 150 grain spitzer bullet. The rifle twist was kept at the initial 1 rotation in 10 inches (1in 10) twist. I have loaded and shot bullets in a similar barrel with weights from 147 grain to 220 grain and all seem to do well for me. This may be explained by accuracy requirements. I do not shoot bench rest, so my accuracy expectations - requirements are not as great. That could be the explanation. In anecdote, I do have an older rifle with a well used barrel. The rifling is so worn (bad) one can identify the type of bullet at 25 yards. The bullet struck sideways. (I did rebarrel that rifle.)
@Swampytheroot3 ай бұрын
Good stuff. Nice presentation.
@sdkweber3 ай бұрын
Thank you very much. Thanks for watching and taking the time to post.
@rokkinjohann3 ай бұрын
Yep, I am gut-twisted every time someone uses that term "over-xxx". See, I can't even type it. My question always was, "For a given cartridge/bullet combination, as the twist rate increases and one moves from under-stabilized (big groups on paper) to marginally stabilized to stabilized (smaller groups) at what point do you have too much stabilization? On the other hand, an excessive spin is easy to detect by midflight disintegration. 'Overbore' is another imprecise term I am loath to use other than to point out its users employ it to put on a facade of knowledge.
@guncaine13 ай бұрын
Very well explained
@sdkweber3 ай бұрын
Thank you for watching and posting Rich.
@user-iy4gw2sh7v3 ай бұрын
An overstabilized bullet shows itself only at subsonic speeds. When the cone of air stops helping it to fly straight, then due to high revolutions around its axis, the nose of the bullet begins to look up. An unstabilized bullet begins to behave unpredictably at 100 yards. This is clearly visible on paper. The grandfather in this video is mistaken
@GeirMeyer3 ай бұрын
Beautiful work
@sdkweber3 ай бұрын
Thank you very much Geir.
@tropocal23433 ай бұрын
*Look into boat-tails becoming unstable upon leaving the muzzle, due to gasses escaping around the base causing wobble, the exact opposite of what it was designed for.*
@DibsInNH3 ай бұрын
Thank you! This was very informative.
@sdkweber3 ай бұрын
You are welcome. And thank you for watching and posting.
@HorstMichel-mh7gv3 ай бұрын
Thanks for this.
@sdkweber3 ай бұрын
You are welcome Horst. And thank you for watching and posting.
@hopewilliams67053 ай бұрын
Well when Eugene Stoner originally designed it was 1 in 14 and then to 1in 12 shoot the original 55 grain and lighter coming from its parent caliber that was used for varmint hunting
@russr3 ай бұрын
he went with minimum twist that was the standard at the time...
@jasonshults3683 ай бұрын
The point was to have a bullet that yawed and tumbled in tissue. This was tested extensively.
@andywilson50493 ай бұрын
Are you also going to think about copper bullets as they are longer than lead bullets at the same weight?
@sdkweber3 ай бұрын
Good questions and yes. The same concept holds true with copper bullets. We need to stabilize them but not over-spin them. I suspect however, that the homogeneity of the copper will reduce the imperfections within the bullet and MAY decrease the effect of over-spinning, that is, a degraded precision of our groups.
@lawerncemiller65573 ай бұрын
Shooting lighter 223 bullets even at 223 velocity's with a 1-7 twist rate damage's the thin bullets jacket an shape causing poor accuracy at even higher velocitys like the 220swift with a 1-7 twist rate might break apart in the barrel or shortly after leaving the barrel and with the slower twist rate wont stabilize heaver bullets a lot of older rifle calibers were made this way such as 270,25.06, 220swift and more and all of them would have been much more useful for hunting a wider range of game if they would have been made with a faster twist rate you can overcome this problem by shooting solid copper bullets in lighter weights they won't deform from faster twist rates an gives higher bc numbers rifles with slower twist rates will forever only shoot lighter short bullets well without changing the barrel
@russr3 ай бұрын
thats not over stabilized... thats just exceeding it construction.
@Ode-3 ай бұрын
Contact surface friction in barrel rifling is actual reason, deforming copper jacket and destroying bullet "perfect" shape.
@Mike-xi4zt3 ай бұрын
Precision bullets get turned into non precision bullets after they are swagged by the barrel rifling. So I am of the opinion that the barrel rifling and how the bullet enters the rifling swagging die/barrel is highly influential on accuacy.
@aaronneumeyer55723 ай бұрын
I really enjoyed this video. So is the bullet sized slightly larger (224 in a 223 and 308 in a 300) so that it has to be slightly squeezed to better engage the rifling? I'm also curious to read your reply to Mike-xi4zt's comment below should you respond to it. I've seen some of the slugs that Taufledermaus shoots on his channel that through the use of a high speed camera seem to show no spin and yet hit the target. Perhaps while not 'finned' it's because the slugs have unusual shapes that mimic them? Thanks as always!
@sdkweber3 ай бұрын
Thanks for watching Aaron. You got it right. The bullet is wider than the distances across the lands. This forces the lands (rifling) to bite into the bullet and engrave fired bullets with the firearm's rifling. The naming though can sometimes be just marketing. For instance a .300 PRC shoots a .308 bullet, but so does the .308 Win. and .30-06 and .30-30 Win. A .220 Swift shoots the same bullet diameter as a .223 and .22-250. I have not seen Taufledermaus' videos. I will look it up. Take care Aaron.
@brucestarr44383 ай бұрын
No. the distance between grooves is 0.224, the distance between the lands are smaller and that is where the bullet is squeezed.
@sdkweber3 ай бұрын
@@brucestarr4438 Correct. The diameter across the grooves is .224. I may not have answered Aaron's questions clearly.
@Hobo-Henry3 ай бұрын
I've noted that when hand load testing if i load a match bullet at say close to 275,000 RPM it tends to be more explosive (fragment) at around 75-100 yards but will expand at longer range 200-300 yards. And at around 350,000 RPM it can literally explode in flight. this is hog hunting
@sdkweber3 ай бұрын
That number (350,000 RPM) has been cited by others as the point of excessive spin in some cartridges
@Crazy-cg9cq3 ай бұрын
Would that increase spin drift making it inaccurate or maybe disintegration ?
@Mike-xi4zt3 ай бұрын
Faster any object spins the more stabile it becomes, even If it is out of balance. Rotational velocity can exceed outward acceleration due to Non balance center of gravity. Any "center of pressure" is exceeded by rotational gyroscope stabilization. The only time overspining a bullet affects accuracy is when the heat and rational velocity exceeds the bullets ability to maintain its shape, and causes it to deform or fly apart. All rotating objects are more stabile the faster they rotate.
@sdkweber3 ай бұрын
That is what I thought for years also. Then about a year or two ago I read Jeff Siewart's book "Ammunition Demystified" and he explained the effect of over-spinning a bullet. That made me dig into this and do much more extensive research and much more reading. I tried to explain this in the video (I believe Hornady did a pod cast and discussed this also). Bottom line, it is very real and over spinning a bullet will harm precision and this is primarily due to integrity issues of the bullet as over-spinning accentuates: Errors in bullet construction. Differences in a bullet's axis of symmetry relative to it center of gravity. Differences in a bullet's axis of symmetry relative to its axis of inertia.
@Mike-xi4zt3 ай бұрын
@sdkweber Physics says rotational velocity Can Exceed outward movement velocity. That means even if it is out of balance it can balance itself out with enough rotation. vehicle wheels are on a rotational speed limit, or you get a citation. You can spin bullets as fast as you want. Enough rotation will zero out errors in bullet construction. Not enough rotation will cause insufficient stabilization, wobbling, or tumbling. I can give you the physics equations, and plugging in numbers will illustrate what I am saying. Unfortunately, there are so-called experts that are not really experts.They don't understand physics. The bullet goes to sleep theory is complete mythology nonsense. Nowadays you can watch NFLs longest passes on youtube and play them in slow motion. The footballs thrown wobbly stay wobbly until they are caught. They do not go to sleep. A top wobbling and falling over is in contact with a stationary object which changes the forces acting on the rotating top. A bullet flying through the air does not have its point sitting against a non moving object and does not straighten out like a top does and does not wobble around the point that is in contact with a stationary object. Barrel rifling tears up they finish on the bullets and has an Effect on the integrity of the jacket. If you spin them Enough to make them Bulge or come apart They will not Shoot straight. That is literally the only type of "overstabilization" that can exist. All the rest is BS.
@sdkweber3 ай бұрын
@@Mike-xi4zt Feel free to post links to the equations. I would like to see them. For me, I am siding with the ballistics experts like Siewart on this. His work is also physics-based as well as experimental.
@Mike-xi4zt3 ай бұрын
@@sdkweber I watched the podcast with jeff seiwmart. Duplex loads been around forever. Elmer Keith was doing that before World War II. Gain twist has been around for a hundred years artillery has steel case ammo and they use a copper ring to engage the rifling for gain twist. Regular Small Arms copper bullets in the whole side of the bullet engages the rifling in Gain Twist causes eccessive bullet deformation. I would agree with him on there is no magic cartridge. A bullet being pushed down the barrel with 60,000 PSI does not know what cartridge case it came from and does not care. To say a certain cartridge generates a special magic fairy dust 60,000 PSI is ridiculous. I have an electrical engineering degree and I've taken plenty of physics classes. This guy was telling the story about shooting the tank round steel rods through three targets and couldn't hit the last Target. And comes up with some calculation of maybe there was a stone in the first two Targets. Why not just remove the first two Targets and see if you can hit the last one to see if there's something else going on. That's called dumbass logic. In a bullet there is a moment of inertia and center of gravity. If there is an imbalance in the moment of inertia when a bullet is flying through the air if it is rotated fast enough it will rotate around the moment of inertia in combination with the center of gravity whatever the net force is of those two for the bullet. The bottom line the bullet will be stable if it is rotated fast enough whether it is rotating around the moment of inertia or the center of gravity or both simultaneously. "pressure force" is already being overcome by the rotational conservation of kinetic energy. The pressure force will be equal around the bullet because of the direction of flow of air. If you're pushing the same amount around all sides of the bullet the net force is zero.
@Mike-xi4zt3 ай бұрын
@@sdkweber KZbin doesn't let you post links in comments
@mikejohnson40153 ай бұрын
The RPM of the bullet can be calculated knowing twist rate and velocity.
@sdkweber3 ай бұрын
That's right Mike. And these bullets are spinning at astonishingly high RPM... especially considering a circular saw spins at about 7,500 RPM. Thanks for watching and posting.
@brucestarr44383 ай бұрын
Your .220 Swift is fast. But not as fast as P.O. Ackley's 22 Eargesplitten Loudenboomer. It would be interesting to see how fast it would be with the new slower burning powders.
@sdkweber3 ай бұрын
I had never heard of that wildcat cartridge. Quite interesting and certainly a cool name too.
@user-sv1xg9ow5c3 ай бұрын
Greetings from Ukraine ))
@sdkweber3 ай бұрын
Hello and thanks for watching. Take care and stay safe.
@CasperInkyMagoo3 ай бұрын
I’m working on a subsonic load for a 20” 308 with the standard 1:10 twist and I’m starting to get a bit frustrated. I started experimenting with heavier bullets aiming for the same ~1050fps (trail boss powder) to increase muzzle energy and it seemed as if no matter what I tried the gun didn’t like it. (180, 190, 220). The rifle went from shooting quarter sized (supersonic) groups at 100 to 6” at 50 (subsonic) Are you suggesting I stick with the 168 or maybe something even a bit lighter, since I’m decreasing velocity significantly?
@sdkweber3 ай бұрын
I think you are seeing actual stability issues. I have the same issue with my RPR as it shoots heavier (longer) bullets poorly but does a good job with the 168 gr. bullets. Look for a shorter bullet and give that a try or stick with the 168 gr. range. Speer Gold Dots are pretty short bullets for their weight and they may make a heavier bullet you could try. Thanks for watching and posting.
@CasperInkyMagoo3 ай бұрын
@@sdkweber Thanks for the reply. At this point if I could get 2MOA out of it subsonic I'd be thrilled.
@sdkweber3 ай бұрын
@@CasperInkyMagoo I understand what you mean. I see the .300 blackout uses a 1:8 or 1:7 twist. That's is how that rifle can shoot the heavy (long) 200 gr. + bullets.
@BigTimberLodge3 ай бұрын
Would love to chat with you about 300WBY.
@sdkweber3 ай бұрын
Let's discuss Big Timber. I have a .300 PRC and we can compare notes.
@brianmount70363 ай бұрын
What does an overspun bullet look like on groups on paper.flyers,large groups??
@sdkweber3 ай бұрын
Yes, your groups will experience increased dispersion and you will see more flyers.
@CasperInkyMagoo3 ай бұрын
You won't see it in terms of the hole in paper, like a keyholing bullet if thats what you mean.
@sdkweber3 ай бұрын
@@CasperInkyMagoo That's right. Over-spun bullets are stabilized so no keyholing. But the groups will be large.
@joearledge13 ай бұрын
He said it best when he said overs spinning accentuates the defects in a bullet aka highlights the flaws in the bullet as none are perfect. The best illustration I've seen is in 5.56/ .223 when, a few years ago, the channel, Johnny's Reloading Bench got a new 20" 1:7 match barrel to replace an 18" 1:8 match barrel for his ar. He did a video breaking in the new barrel and comparing it to the old barrel at the same time. He used known good loads in various weight projectiles that he had worked up in the 18" over a few years. The "old" 1:8 was stacking them pretty tight, the new 1:7 was "meh..", it wasn't terrible, but it wasn't impressive like the 1:8 was. Basically, if you're twist is too fast, the "precision window" for amazing loads gets smaller. If it's too slow the length/weight of bullet you can successfully shoot becomes restricted. If the twist rate is just right, it stabilizes a wide range of lengths/weights(unless you are specifically targeting a "weight class" ex: only long heavy bullets or only short light ones) and is very forgiving with components and loads, leading to a larger "precision window". Johnny went on yo work up more loads with the 1:7 20" and it always just seemed like impressive groups were harder to come by than with the 1:8 18". You can check out those videos on his channel and you'll see exactly what I'm talking about. Another example is 308 shooters. The "standard twist" is 1:10, though it's not hard to find others twists in 308. Most legitimate competition match grade barrel are 1:11.25". Apparently the 1:10 seems to be over spin, 1:12 seems to be barely too slow for 175gr and higher, 1:11.25 seems to be the sweet spot for 308 roughly 150gr to 200gr. My guess is the extra 0.25" came from competition guys with a healthy dose of OCD trying to figure out "the perfect" twist. Anyway, hope that helps some.
@carlpreston16803 ай бұрын
So that was one of my questions if you overspin a bullet because of the wrong bullet for the given twist rate can you slow its velocity down to counteract the effects and also how does barrel length affect twist rate for example a 30 cal bullet and a 1 in 10 twist rate barrel 22" vs 24" vs 26" Will the 26 be able to stabilize a long heavy for caliber bullet even though it still has a 1 in 10 twist
@Spartan001b3 ай бұрын
Physics
@ronaldmontgomery84463 ай бұрын
Put the centrifugal force into the equation. An over spun bullet will fly apart . The center of gravity and the center of mass are not in the same place for a bullet but a foot ball they are. Make a bullet where the front and the back are the same and spin rate won't matter. Modern bullets do not arc over like a foot ball.
@sdkweber3 ай бұрын
Good explanation. Thanks for posting and watching, Ronald
@jasonshults3683 ай бұрын
That's not true, Ronald, and extreme long range targets prove it.
@ronaldmontgomery84463 ай бұрын
@@jasonshults368 It is only 5° at 4 miles. The hole in the target will still look round.