I picked up one of my spent slugs at about 150 yards or so, off of the range field the other day.

I realized just a while ago, that it had an interesting story to tell. Here's a pic of a section of the slug.



In fact ... might be fun to see what you see. And, Cedric ... are you out there Son? This one should spark something to you.

Let's see what Sherlock can scrounge out. I have some opinions. How about you? There's no real test. No wrong or stupid answers. Try it.

It'll be a good thing for this evening's entertainment.

Gary



slug laying atop the machinery that made it's 1 in 12.5" twist barrel. Perfect match.



Edited 1 time(s). Last edit at 06/10/2010 07:54PM by barnespneumatic.

You guys shooting at axe heads again?

Yup, axe heads at 75 yards!

... you forgot to mention the picture.





Edited 1 time(s). Last edit at 06/07/2010 11:06PM by barnespneumatic.

Man ... "tough room"

I thought that was the neatest thing I'd seen in a long time. I expected a bunch of discussion.

BTW ... forum has been crawling again for me. And, I've placed this comment twice .... neither time in this location. I don't know what's up. It's screwed up again. Crashes every time I try to post.



Edited 1 time(s). Last edit at 06/08/2010 03:06AM by barnespneumatic.

I thought you'd hit the edge of the steel targets and then dug it out of the dirt uphill. So...you're saying that was just a lucky hit on a random rock behind the target?

Sean,

That's right. It was just an odd find. A slug that had skipped off a stone, but left the track of intersecting that stone. It struck me that it recorded it's rate of twist relative to it's forward movement.

I've been surprised this post has gotten such little serious comment. I figured people either found it of no interest, or just didn't believe me.

Take a look at the slug laying atop a section of the greasy machinery that created the rifling inside the barrel.



My observation was valid. The marks on the slug are at the identical twist rate of the machinery that created the rifling.

This "RPM" issue with rifling is interesting. It's the "force" of, for example, 100,000 rpms". It's not that the slug itself has spun 100,000 times. The artifact I picked up off the range, shows that the slug lands at about the same twist rate it left the barrel. And, in this case, this was a fast twist barrel.

Gary



Edited 1 time(s). Last edit at 06/10/2010 07:55PM by barnespneumatic.

Here's what I saw:

We have a snapshot of a microsecond in time. The slug was obviously moving forward, and rotating. After it punched the target backer, the slug flew on to probably 75-80 yards where the hill starts to rise. As it made contact with the ground; it landed on a stone and plowed over it's surface before it skipped off to rest where I later picked it up.

The grooves on the lead slug describe a counterclockwise rotation (from my left hand rifled Barnes barrel). And, the groove spiral records it's rate of rotation, relative to it's rate of forward travel. This is why I mentioned Cedric. During our rifling discussions, Cedric mentioned that when you watch a very high speed video of a bullet passing a given point; the slug seems to be barely rotating at all. Looks like maybe a quarter turn while it passes the target object on screen. I've seen those videos too. They look just like the grooves on this slug. It rotated maybe a quarter turn while it dragged across the surface of the stone.

I thought that was a very interesting physical evidence of what we've discussed before. It also revisits that difficult to rectify image of rpms as they relate to the forward travel of bullets. When I hear a hundred thousand rpms, I'd expect the grooves on such a bullet as I found, to look like the threads on a bolt. But, they look just like the videos.

Gary

Test. I've been having trouble with the forum. How about others?

Everytime I post, it crashes. And, it doesn't move the new post to the top ... or flag it with a red number.

Gary

Gary,

I passed. I was able to interpret that from the picture. That slug was a great witness.

Lon

DANG ON IT GUYS, i wanted to say it first.

It took me exactly 5 mins to continuously look at it and then i just laughed out loud. The wife said "what, you looking at more air gun stuff?" and i just gave a low caveman type grunt...UHHUHHH?

But yes, i left a streak that resembles rifling twist.

You guys gotta start waiting for me to join in...........gall dangit!!!

I really wish there was a GOOD VIDEO of a close up shot of a bullet shot out of a rifle. But, i just simply can't believe a bullet could structurally stand up to revolutions of 100 grand - 300 grand. Thats it, i'm going to the hornady lab with my cameras and a note pad and i'm gonna make em prove it to me...lol

I think I have a picture somewhere that indicates...NOT THIS AGAIN! Really! It's not all that odd when you think about it in the big picture,

Take a 1 turn in 12 inches barrel and fire a slug at 1000fps, that's 1000 turns per second = 60,000 rpm. That sounds really fast but it only lasts a very short time, far less than it takes to make 60000 spins. Also, even though the turns per minute sound high, it's still only one turn per linear foot traveled...at least until the drag slows the bullet faster than the spin rate but that's going to be a minor change (if any) before the slug hits something....

Think of it this way: The propellor on an airplane that is stopped on the ramp awaiting takeoff spins. But, when that same aircraft starts it's takeoff roll, the propellor tips don't spin anymore, they travel in a helix. They are still making the same RPM but they now have a forward velocity too.

But ... it's not "this again".

I know ya think I don't get the whole helix thing. I do. The centrifical force thing. The throwing a rock out of a tire at fast speed that stays in at slow speed. I get it.

If you line up one thousand shooters, I'd bet you dollars to donuts that 999 of them would swear that a bullet in flight, is spinning like a turbine. It's not. It's turning over once relative to the forward travel of the rifling.

I found a slug that had two grooves plowed in it, with a standing rib between them. They described a left hand twist, at exactly the 1 in 12.5" twist rate of the barrel it was shot from. Doesn't matter if it glanced off a rock, skinned a steel target, or hit a pudding pop ... .... that's a pretty heavy co-incidence. I thought it was interesting.

Gary

We've had a bunch of trouble with the server hosting this forum over the past few days. I've commented on it multiple times on this thread. Asked for confirmations of what you have seen. As you'll note ... not one comment responded.

The host said they were having maintenance issues. It's been coming and going. Evidently we'll never know if I'm the only one seeing it, other than Jim, who's been interfacing with the host.

Gary

Yes, bullets spin at pretty high RPM rates. No they don't really spin 100,000 or 300,000 times or whatever on the way to the target. Why not? Well, it's because a bullet is almost NEVER in flight for more than a fraction of a second at normal ranges, let alone a whole minute.

The only way to get a bullet to stay aloft anywhere like that long would to be to fire it off Mt. Everest with the barrel elevated to 30 or 45 degrees or so. Even tank main gun cannon rounds that routinely hit targets a couple of miles away are only in flight for two or three seconds. The only projectiles I know of that routinely "hang" in the air for a whole minute at a time would be artillery shells, and even then only at longer ranges. Keep in mind that "long range" for a 155mm shell is in the vicinity of 20+ KILOMETERS.

It's like speculating how much money you could make if you invested a dollar with compount interest for a hundred years. Yes, you come up with some impressive numbers, but they're far more of an intellectual exercise than a real concern.

That's good. I agree. That's the stuff we discussed before and everybody seemed to think was like talking about cutting Social Security.

All I wanted to survey was ... "Can you see the two left hand grooves with the raised rib between .... and can you see that it matches the timing rod with the slug laid atop?"

That's the artifact. That was my purpose in posting the thing. Lon and Cedric seemed to say yes. I'm not getting paid anything to Lobby for this. It was just supposed to be a fun thing that occured to me.

Gary

GB and JERRY,

Just a thought to ponder upon.

Do you guys think that between us 3 with the cameras that we have, we can somehow catch a bullet CLEARLY streaking by? And yes, i know that this camera has limited abilities as compared to a SUPER 10,000 FPS+ camera but, i'm just curious as to whether or not you guys think we could get something showing a bullet or pellet flying by. I should not have said CLEARLY. I should have said an IMAGE of a bullet.....lol.

There are a lot of ways to set up these cameras (from the few experiments i've shot with the camera). So who knows.

Hi Ced.

The things I've seen like you are thinking of, were shot with 10,000 fps or more. I don't think we have the muscle. ;?)

Gary

Jim could perhaps do it with the strobe set up he was talking about before.

JIM, JIM, JIM, JIM, JIM, JIM, JIM, JIM

Hopefully that was enough to get him to try it with the strobe setup you talked of.

I'm still gonna try a couple ideas tomorrow.

Gary, still cogitating on this one. Just tried to open the image of the rifling and there's nothing there. Can you re-post that please?
BTW, I did notice some sluggishness with your site a couple of times I tried to read posts, but all seems well now...
Cheers
Neil

I don't have good data on the site speed as it is only slow for me when I try to grab a minute at work and check-in. Works OK when I get home...

Not to spool you up Gary but the slugs really do spin like turbines! Turbines run in the 10s of 1000's of RPM and props run maybe 1500 or so.

It is neat how the scar on the slug matches the timing rod perfectly.

I'll bet the chances of any given bullet hitting a hard object just exactly so that it shows the rotational effects are pretty slim. And I'll go way out on a limb here assuming that the chances of any given bullet being recoverd after just such a hit AND being matched up with the orginal tooling that made the barrel it was shot out of are WAY smaller than I care to think about.

Yup Jerry...little turbines. Little turbines that run for less than a second before they're mangled beyond recognition. That's a service record that even the infamous Lycoming LTS-101 can't match.