Tumbling rounds

[indianajoe]

Out in AZ recently, we visited the Scottsdale Gun Club and spent some time on range with a rented Springfield 1911 (in .45). I noticed that her target holes were keyholing, indicating that the rounds were probably tumbling.

I got lucky with the timing on this cell phone photo, in which you can see the round tumbling (or ribboning) toward the target:

Not that I'm interested in servicing their rentals, but if this was my pistol, to what would I attribute a tumbling round and what would be the fix?

 

[poisonspyder]

you need a dif twist rate for that grain of ammo. prob shooting a heavy grain i would guess and the gun was designed for a lighter bullet.

 

[rockhopper46038]

^^^, also possible is the rental gun's barrel has a damaged crown.

Heck of a nice photo, too!

 

[CalebToNowhere]

No idea what to tell you, but that is a pretty sweet screen grab!

 

[drgnrobo]

Awesome pic Ive never seen that perspective of a tumbler before.Only thing i can add its possible that the bullet diameter is smaller than the bore (Shot out bore)

 

[indianajoe]

Good info. Thank you, gents.

 

[ghitch75]

i would say the bore is clogged with lead...smooth bore!!!!..no one has cleaned it.....

 

[db1959]

I dont know the guns problem is but I am going to rep you for the photo. Thats an astonishing photo for a cellphone.

 

[gunman41mag]

Bore rifling is worn

 

[thompal]

I'm really surprised to see that it begins tumbling so soon after leaving the barrel.

 

[I Like Firearms]

A SLINKY!!! A slinky, a slinky, a wonderful wonderful toy, its fun for a GIRL and a boy!

 

[climber409]

Nice pic!!! Thanks for sharing.

 

[Wild Deuce]

That is a heck of a ribbon/tumble ... right from the bore, too!

I vote for a shot out barrel (worn rifling).

 

[hoosierdoc]

Interesting pic, but what are we really seeing? A tumbling round I thought tumbles or rotates on its own axis. That would imply the image should be a straight trajectory line but the blur thicker than normal. I'm not saying it's not a cool pic, but what exactly are we thinking we're seeing here? is it a smoke trail? Is it the actual round? If the camera shutter speed is 1/100 and the round is 1000fps, it should travel 10' over the course of the image I think, which means that picture is certainly showing something moving that fast.

I couldn't find other pics online that show this effect to compare against but I would love to find more examples.

 

[Bersalover]

really interesting photo

 

[agreen0170]

Im not sure on what would be wrong with the gun, but that is a pretty sweet picture. I havent seen anything like that before

 

[hoosierdoc]

I'm curious why our senior members with lots of experience aren't jumping on this discussion. It's a very cool picture and I've love to hear their input on the ballistics and physics involved as to what is creating this effect. I've tried my best to find a picture of a bullet "tumbling" in flight and can't do it. It's possible this is a very unique shot and novel to the community.

I downloaded it and saw it was taken on a droid with a 1/15 shutter speed. That really is kinda slow, but it's a phone camera with low light so it's to be expected. Something just doesn't make sense to me looking at this but I can't figure out what. Any other thoughts? If it is truly a "tumbling" bullet, what would cause it to make uneven undulations and move both up and down in an alternating fashion? Is this a shockwave effect? Overhead lights shining off the bullet and being altered by the smoke and shock wave? I dunno but have been thinking about it all day.

 

[indianajoe]

Can't speak for senior members, but I'm satisfied with the info that's been shared to this point: a shot-out barrel, worn rifling, and/or damaged crown fails to stabilize a slow and heavy round, allowing it to tumble. Poorly maintained rental gun + keyholed paper target + a lucky photo = a fairly clear depiction of a tumbling round.

As far as a tumbling round showing a "ribboning" effect, I'm sure it has something to do with photo distortion attributable to the slow shutter speed: 1/15, as you note (and good photo forensics there). Even the 1911 itself looks distorted: the rear of the slide looks nearly parallel to the deck, while the front of the slide appears at an angle of 40 or 45 degrees.

No reports of 230-grain UFOs at the Scottsdale Gun Club. I'm good. Anything more will take us into Warren Commission territory.

 

[scottka]

Maybe this is stupid, but when I first saw it, I thought it was the brass being ejected. The "object" appears larger as it gets farther away from the pistol making me think that the object is actually traveling toward the photographer, no? As in spent brass being ejected to the right and rearward. Or am I missing something?

 

[indianajoe]

Zooming in a bit, this is what I'm seeing: