Does a bullet get longer...

[R.W.Dale]

I was really bored last night at work last night and got to thinking about things dangerous stuff related to bore sizes and bullets and I realized sumpin interesting........

Lets say for example you have a 30-06 rifle with a std spec groove diameter of .308" and features measurement of .300" across the four lands.

Now picture in your minds eye a .308 bullet engraving itself into the rifling. Wouldn't it stand to reason that as the bullet takes the however wide lands onto it's surface that the displaced material must go somewhere? It can't go to the sides because the bullet and bore are already the same size. Thusly does the bullet actually get longer as it gets forced into the rifling in a gun barrel?

 

[brickeyee]

Yes, but if you compute the volume displaced by the rifling it is a very small amount.

If there is a hollow point or other volume within the bullet is is probably just as likely to be reduced (if not more likely).
If the bullet was a solid cylinder it would have to 'bulge' somewhere.

 

[R.W.Dale]

maybe we can get someone better at math than me to do some cacluations

 

[Cannonball888]

Only at rest will the reformed bullet measure longer. In motion it will be offset by the decrease in size according to Einstein.

 

[Jdude]

Cannonbal888:
The dimensions only decrease in the direction of travel,and at such low speeds (compared to light) the effect should be damn near negligible, if not even unmeasurable with modern equipment.

Krochus
Not having done any calculations, my intuition tells me that the metal displaced by the lands that doesn't wedge into the grooves does indeed increase the length of the bullet.

 

[berettaprofessor]

They get shorter and narrower. According to my calculations and information supplied by others from this board, most Magnum rounds have projectile speeds approaching the speed of light in a barrel 20 inches or longer. Einstein proved ages ago that the bullet will appear shorter and thinner to those of us traveling on the Earth's surface at mundane relative speed.

I'm pretty sure this theory also explains why I miss the target so often

 

[mgregg85]

According to my calculations and information supplied by others from this board, most Magnum rounds have projectile speeds approaching the speed of light in a barrel 20 inches or longer.

Huh?

The speed of light is about 983,571,056.4 feet per second. Find me any magnum round that approaches that, even the .17-50 BMG mall ninja magnum wouldn't come close.

 

[Vern Humphrey]

One of the problems with the Barnes X bullet (which was made of solid copper) was the creation of "fins" by the displaced copper. This caused inaccuracy in rifles with tight bores (with a bit looser bore, less metal was displaced, and no fins were formed.)

Barnes solved the problem with the "Triple Shock" bullet, which has bore diameter grooves, allowing the displaced metal a place to accumulate.

Interestingly enough, bullets actually do get shorter on firing -- some of them, anyway. The points of pointed, lead-tipped bullets tend to flatten on firing. This is one reason why polymer-tipped bullets have become more popular -- their tips don't flatten and they have a higher Ballistic Coefficient as a result.

 

[RobertRogers]

And lets not also forget the time dilation the bullet experiences, which, as you know, is caused by the relative speed of the bullet as set forth in the Law of Relativity.

 

[230RN]

Yes, and the technical ballistic term is "smooshed."

mgregg85, you are way off base. I have chronographed my hot-loaded .380 ACP at 983,571,024.3 feet per second many times.

With a short 3" barrel.

This is 99.9999967% of c, or Mach 894,155.5.

Many times.

Noisy, though.

 

[RonE]

Quote:
According to my calculations and information supplied by others from this board, most Magnum rounds have projectile speeds approaching the speed of light in a barrel 20 inches or longer.

Huh?

The speed of light is about 983,571,056.4 feet per second. Find me any magnum round that approaches that, even the .17-50 BMG mall ninja magnum wouldn't come close.

But if you neck the .50 BMG down to one of those old phonograph needles and use the right powder, I am sure you couldn't see the bullet....If you can't see it, it must be at least as fast as the speed of light....I think we call it "warp drive II".

 

[.cheese.]

Whoa...... there's a bullet that travels close to the speed of light?

I want one!

 

[Zedo]

Yeah . . . them there "light" bullets and "light loads" . . .

You can't see 'em. They must be goin' the speed o' light.

On a more serious note:

Lots of gun specs list bore diameter and groove depth.

Hair off your head runs about .002". Hair off your moustache runs about .004".

Sometime take a bullet and push it through your bore. To make it simple, pick a LEAD bullet and run it through something SHORT, like a handgun bore. Start at the breech!

They's really, really tight!

Discovered all this once when my handload "squibbed" because I didn't get any powder into the case. 40 Smith in a Glock. Takes a hardwood dowel and mallet . . .

 

[230RN]

.cheese., I'll send you the loading data for my .380.

I'm sure that with a four inch barrel it will break the light barrier.

 

[vtoddball]

I've only seen bullets get longer if you talk dirty to them and smack them on the brass.

 

[vtoddball]

You know, I think Hornady had a cartridge that approached relativistic speeds and the bullet got there just fine, but the shooter and the target had both died of old age in the meantime.

 

[Loomis]

Really! How many laps around the solar system did that bullet do?

 

[Jdude]

Just once, but it threaded every one of Rosie's belt loops.

 

[physics]

:banghead:

 

[230RN]

Oh, wait! Stop, stop, stop!

I misread my chronograph!

It wasn't 983,571,024.3 feet per second I got out of my .380!

It was 983.5710243 feet per second!

My bad!

Oh, well. What's six orders of magnitude between friends anyhoo?

Darned Nixie tube readout. Cain't hardly see the decimal point nohow.

 

[Dave P]

"And lets not also forget the time dilation the bullet experiences, which, as you know, is caused by the relative speed of the bullet as set forth in the Law of Relativity."

You guys need help, obviously.

The Law of Relativity, as it applys to bullets in flight, generally says that the bullet (being effected by the Correlis Affect) the will be displaced relative to the bullseye upon impact.

PS Nixie tubes?? You must be about tens days older than a stone to know about nixie tubes!

 

[berettaprofessor]

mgregg and physics; I assume the two of you are either engineers or physics professors and don't get the jokes......sorry to try a little lightheartedness.

 

[vtoddball]

Heisenberg is out for a drive when he's stopped by a traffic cop. The cop says 'Do you know how fast you were going?' Heisenberg says 'No, but I know where I am.'

 

[MinnMooney]

230RN - By Gove, I think you've got it!

Yes, and the technical ballistic term is "smooshed."

I have chrono'd my hot-loaded .380 ACP at 983,571,024.3 fps many times.

With a short 3" barrel.

This is 99.9999967% of c, or Mach 894,155.5.

Many times.

Noisy, though.

Oh, well. What's six orders of magnitude between friends anyhoo?

Darned Nixie tube readout.

230RN : You are just too much! Have you ever thought about writing humor for a living? I have a feeling you'd do pretty well.

 

[mgregg85]

mgregg and physics; I assume the two of you are either engineers or physics professors and don't get the jokes......sorry to try a little lightheartedness.

Kinda figured you were joking, thats why I threw in the part about the .17-50 BMG MNM.