Bullets corkscrewing?

[44Blam]

A buddy of mine was shooting .22 tracer rounds at night and said it looked like they were corkscrewing along the flight path.

Anyway, is a bullet corkscrewing an indication of a problem or are they generally going to corkscrew a little?

[Mk42gunner]

I've seen that when shooting .22's at night with a really bright light, (coon hunting, get your mind out of the gutter). I think it is light reflecting from a not totally flat base.

With the apparent size of spiral I was seeing, about 10-12" diameter, you would never hit the target. I don't remember having any unexplained misses when this happened.

Robert

[uscra112]

A bullet not launched straight from the muzzle will indeed corkscrew in flight, as Dr. Mann showed us in detail over 100 years ago. An out-of-square base is a prime cause, and it would not surprise me if you found that the bases of your tracer rounds were less than true.

He also showed how a rifle can shoot tight groups at a given range even when the bullets are spiraling in flight.

[tomme boy]

See it all the time with the sun at my back shooting out to 200yds with a 22rf. You have 2 different spins going on. You have the bullet that is spinning then that is also in another cork screwing spin that you see.

[M-Tecs]

The only time I have actually seen it was with varmint bullets that are driven harder than they can withstand. Some would just blow and some would corkscrew until they hit the ground. On 22 tracers it could be an out of balance issue or an optical illusion. Easy enough to test. If it doesn't change POI for windage at various distances it's not corkscrewing.

[Gofaaast]

Think simple physics. If you have a round that groups 3” at 100yards it’s corkscrewing. Magnify that over several hundred yards with a tracer that gets less ballistically stable the further it travels and that group may be 36” at 500 yards and really magnify the corkscrew. It’s been several years since I fired tracers I loaded in my 300 wby. My initial loads ignited about 500 yards downrange and remained lit over 1000 yards i estimated. I downloaded them as low as possible and they lit sooner. I don’t recall any corkscrew affect even right before they burned out but they were traveling much faster than a 22lr. I think a 22 corkscrewing would be normal.

[Don Purcell]

What happened to me and I'm still trying to wrap my head around it as it has not happened before with my three Sharps rifles.. Shooting my muzzleloading Pedersoli Metford-Gibbs .45 cal. Long Range rifle with 540 grin paperpatch slugs at 200 yards it shoots patterns. When shooting 500 yards in the Mini -Creedmoor at Friendship it would hammer into about the size a little bigger than a baseball cap. I guess just don't shoot at 200 yards. Even 100 yards can be frustrating at times. Go figure.

[303Guy]

Dopplar radar chronographing shows at long range what appears to be a bullet cyclically slowing and speeding up again. That's the corkscrew motion at the steep end of the trajectory. The SMLE with MkVII ammunition was known for the groups tightening up down range, making it a better long range target rifle. These rifles had to be propery packed to get good long range results - thats the cork packing in the forend.

The early 375 Holland and Holland magnum had a problem with African big game hunters because of bullet yaw (which causes corkscrewing) at closer ranges because it adversely affected penetration. At longer range the yaw settled down (and the bullet slowed too) greatly improving penetration. Apparently, in response to complaints and requests for a heavier bullet loading, Holland and Holland said it was designed as a long range rifle. But they relented and produced a heavier and slower loading which the hunters of the day prefered, that did not yaw.

Spiral bullet path. Here one can see how a tight group can be obtained at a particular range (mostly longer range I would think) in spite of the corkscrew. It also explains the odd shaped groups we sometimes get.

https://i.postimg.cc/25t6w23Y/Spiral-Bullet-Path.jpg (https://postimages.org/)

[M-Tecs]

http://bulletin.accurateshooter.com/2013/07/over-stabilization-of-bullets-why-is-too-much-spin-a-problem/

[samari46]

Saw the same thing when shooting 45acp from a semi auto at 100 yds. Bullet was actually corkscrewing on its way to the target. Had a good spotting scope and it was actually funny to see it corkscrew or wobble down range. Frank

[Don Purcell]

Thanks 303Guy and M-Tecs, what you both provided is what I've suspected but have wondered why my Sharps rifles do not exhibit this but my Pedersoli does. May cut my long range charge back a bit to see what happens at closer range. Also have Mann's The Bullet's Flight and need to dig further into it.

[upnorthwis]

During an IHMSA match my spotter told me my J-words were cork-screwing. Pistol was 10" TC in .357 Mag.

[waksupi]

It takes some distance for a bullet to "go to sleep".

[fredj338]

Well all bullets rotate about their axis. The amount will be determined by the bullet base & any voids internally or externally. A true tracer gets unstable as the compound in the base burns. I would expect a less than tight spiral.

[charlie b]

If you want to see a large spiral, find an older M2 Machine gun barrel, fire it until it gets too hot, and watch the rounds start to make big circles going down range. M60's used to do that too, but, not quite as dramatic as a .50cal bullet (especially at night :) ).

Yes, I know it is not from the same thing as what you all are experiencing.

[beagle]

Firing .38 Special loads out of a M1894 Marlin on a 100 yard range over snow through a 10X Weaver you can easily see them corkscrew and then lose them as they drop into the target. Doesn't seem to affect the grouping abilities.
I've seen the same thing out of a .45 ACP over water. Same deal with an M1 through a Unertl 60X spotting scope at 600 yards./beagle

[Texas by God]

We were shooting rabbits at night from the truck in West Texas years ago; Cuz and I in the cab running the light, my son shooting from the bed. He missed an old Jack just as his Remington 597 ran dry. I handed my Enfield .38 to him- 148 hbwc about 500 FPS- in the spotlight, we saw the bullet loop de loop and smack the hare hard. We had him shoot the rest of the cylinder because it was so funny.

[44Blam]

Actually, thinking about it...
My dad gave me a .38 snub nose with a bunch of ammo from K-Mart when 50 rounds of 38 special was $5.27...

I took that pistol and the bullets and I could not get those bullets on paper at 20 yards. I saw them spiraling... I just thought that the pistol was a ***. Maybe it was just the loads? I gave that pistol to a neighbor that was worried that people might invade their place. Well, they moved away and so did that pistol.

But when I shoot my hand loads, I don't see a spiral. With rifle rounds, I hit the same POI at 100 as I do at 110 and 90... At longer range, we tend to set the spotting scope behind the rifle and I have yet to see a round actually spiral. You do see the distortion in the air and the boolit if you get a low enough angle...

But when casting, I do not take any boolits with wrinkles OR a hole in the base. All boolits must have a crisp, sharp base and have good fill out. So, they generally are within 1% or so weight. Maybe slightly greater percent for small boolits...

[44Blam]

Come to think about it, we sometimes shoot reactive targets like rubber balls...

The real fun is keeping them moving and bouncing - you have to continually reaquire and predict where to shoot. If the boolits spiraled a lot, this would be nearly impossible...

[Larry Gibson]

In many instances when a bullet has pitch and/or yaw on exit we see the spiral effect as shown in 303Guys post #8. The bullet most often does "go to sleep" (the pitch and/or yaw settles out) at some distance from the muzzle as waksupi mentions. However, the "corkscrewing" or "spiraling" in larger deviation from the intended flight path, as seen by numerous other posters here, is evidence of the "helical arc" a bullet takes in flight when the imbalances are overcome by the centrifugal force of the RPM. What have mentioned here are most all examples of what happens to bullets, both cast and jacketed, when the RPM Threshold is exceeded.

[kens]

yes, I believe in the corkscrew trajectory. you can print that by setting targets at various yardages, leave your sights ALONE, and shoot groups at the different ranges. you may see a left group, right group, high group, low group, even though all groups may be tight group it appears your sights are off. But no, sights are fine but you seeing the corkscrew trajectory at various yardages.