“BARREL MOVEMENT BEFORE THE BULLET EXITS”

[Edsel]

Bryan Litz’ video was demonstrating how a rifle barrel moves (or perhaps contracts?) by a little bit before the bullet even exits the barrel.

Is the apparent barrel movement:

(1) An artifact due to gases exiting before the bullet

(2) Secondary to the barrel metal behaving in a fluid state during high impulse, with the muzzle contracting rearwards while the areas proximal to the breech and throat are expanding sideways?

I suspect the latter…

During high impulse events, solids may exhibit properties more akin to liquids.

For instance, a bullet cratering on impact resembles the propagation of a water droplet…

 

[Edsel]

…just like in “The Matrix!”

 

[Edsel]

Looking into this would actually benefit from a real FEA exercise instead of some bubba spouting the word “harmonics” and “physics.”

 

[Edsel]

Another video suggests that the typically imagined “OBT Harmonics…”

…a phrase I casually throw around despite my really superficial understanding of it all…

…does not occur the way we suppose they do.

Perhaps this model’s a better representation?

 

[Edsel]

Just had an awful flashback…

Harmonics!!!

Oscillation!!!

Frequencies!!!

There was even this “moderator” on another forum claiming that something would “violate the laws of motion…”

Wow!

Brought to you by us bubbas who can’t even spell “muzzle brake” properly

 

[ma smith]

coriolis effect for sure

 

[Mike Casselton]

Just had an awful flashback…

Harmonics!!!

Oscillation!!!

Frequencies!!!

There was even this “moderator” on another forum claiming that something would “violate the laws of motion…”

Wow!

Brought to you by us bubbas who can’t even spell “muzzle brake” properly

It's Muscle Break. Duuurrrr!

 

[Csafisher]

Why would the barrel contract?

 

[AccuSol-ERN]

Regardless of the science at the micro level......there are external influences at the macro level that ultimately decide point of impact.

Over the years, I have seen too many shooters chasing the reloading minutia, while never learning/practicing shooting techniques that have a more substantial improvement on point of impact.

The science is neat to talk about, but lets face it......how much variability is there in barrel steel composition, barrel bore dimensions, barrel bore straightness, bullet jacket composition, bullet size, bullet true balance, environmentals, rifle peripherals, etc.

I look for patterns and trends. In my observation straighter barrels seemmore tolerant in absorbing the above variables. Also, I get measurably better chambers with conventional 4 groove barrels. Super consistant ammo makes tuning or seating depth easier/better. I don't have time to figure out the science.

Ern

 

[Edsel]

It's Muscle Break. Duuurrrr!

Ya mean, "It be called Muscle Break."

Thass raaaht!

 

[Edsel]

Why would the barrel contract?

Perhaps it be called Tacticle Detumescence, in warriertalk!

 

[Schütze]

I sure hope you get extra points for your efforts.

 

[Csafisher]

View attachment 8509179

View attachment 8509173

lol ok…..

 

[Im2bent]

View attachment 8508935

Another video suggests that the typically imagined “OBT Harmonics…”

…a word I casually throw around despite my really superficial understanding of it all…

…do not occur the way we suppose they do.

View attachment 8508936

Perhaps this model’s a better representation?

Potato.....potahto

 

[Secant]

Self image

Public image

Sometimes it be like that.
But don't worry scrotes, there are lots of tards out there living really kick ass lives.

 

[Edsel]

I don't have time to figure out the science.

Ern

Thet's why Litz be Litz, an' we be some no - account idjit bubbas!

And that's why every other rapidly developing country overseas is EASILY eating our lunch.

 

[E. Bryant]

Are we really going to get wrapped up in attempting to predict the deflection of a 1.35"-diameter steel rod during the first few milliseconds after firing pin impact when the rifle is being held by a twitchy bag of flesh?

 

[Edsel]

Are we really going to get wrapped up in attempting to predict the deflection of a 1.35"-diameter steel rod during the first few milliseconds after firing pin impact when the rifle is being held by a twitchy bag of flesh?

Twitch

Twitch

Twitch

Posting from the range...

Dang, it be gettin' cold 'ere an' there be shrinkage in th' netherplaces!

 

[cas6969]

This is easy enough to test. You just need to build a straight line test firing jig, mounted to a solid immovable base, and then buy an $80k slo-mo camera.

 

[R_A_W]

 

[powdahound76]

This is another example of why fools do fools errands “in the name of science!”



Focus on shooting with a bipod and rear bag, off a pack prone or seated, tripod, tree branch, fence post, etc and be a solid 5 shots at 1 MOA at 800-1000 yds shooter.

my old friend Foul Mike would challenge me to shoot paper at 600.
Excellent exercise. Harder than you think.
He never worried about this minutia and very likely took more cold bore 1000 yd shots with first round hits on a target 1 MOA in height and 1/3 MOA in width in a year, than most in their life.

 

[cas6969]

"If you're trying to do less than I'm doing, you're stupid. If you're trying to do more than I'm doing, you're stupid."

Standard internet answer.

 

[powdahound76]

Wrong again old man

 

[Edsel]

Yep!

Ah’m not hearin’ dem deer an’ coyotes complainin’ none, JimBob!…

 

[msgriff]

This is easy enough to test. You just need to build a straight line test firing jig, mounted to a solid immovable base, and then buy an $80k slo-mo camera.

They kind of already do that, except maybe the slo-mo camera part. Benchrest rail gun competitions are fascinating.

 

[joetuono]

Bryan Litz’ video was demonstrating how a rifle barrel moves (or perhaps contracts?) by a little bit before the bullet even exits the barrel.

Is the apparent barrel movement:

(1) An artifact due to gases exiting before the bullet

View attachment 8508908

(2) Secondary to the barrel metal behaving in a fluid state during high impulse, with the muzzle contracting rearwards while the areas proximal to the breech and throat are expanding sideways?

I suspect the latter…

During high impulse events, solids may exhibit properties more akin to liquids.

View attachment 8508915

View attachment 8508916

View attachment 8508913

View attachment 8508914

For instance, a bullet cratering on impact resembles the propagation of a water droplet…

The video is labeled “gun moves back from here” not “barrel moves back from here”. Going by just this I’m pretty sure the video is to demonstrate that the bullet is still in the barrel during recoil. Most people believe the bullet exits the barrel before recoil happens.

Could be wrong though, wouldn’t be the first time

 

[Edsel]

The video is labeled “gun moves back from here” not “barrel moves back from here”. Going by just this I’m pretty sure the video is to demonstrate that the bullet is still in the barrel during recoil. Most people believe the bullet exits the barrel before recoil happens.

Could be wrong though, wouldn’t be the first time

Yeah.

Sent a message over to Litz, asking if they had a video of the entire rifle...

Hopefully he'll respond.

It'd be interesting to see if everything moves rearward prior to the bullet exiting, as I've never seen a Bomb Calorimeter move during combustion

 

[gwood]

Gee, if only someone like Harold Vaughn had written a book about this 25 freakin' years ago...

 

[Edsel]

Gee, if only someone like Harold Vaughn had written a book about this 25 freakin' years ago...

We have someone of similar caliber who goes by "Varmint Al."

 

[Ronin22]

The price of tea in China means more...

 

[Sum Ting Wong]

Recoil begins as soon as the projectile starts to move. Newton’s third law.

 

[Im2bent]

Recoil begins as soon as the projectile starts to move.

Newton.......Are we talking about Newton?!?!?!?!??!?

 

[Csafisher]

View attachment 8509409

Yeah.

Sent a message over to Litz, asking if they had a video of the entire rifle...

Hopefully he'll respond.

It'd be interesting to see if everything moves rearward prior to the bullet exiting, as I've never seen a Bomb Calorimeter move during combustion

I’m not sure what you’re smoking. But it must be good.

 

[Im2bent]

I see they used a real mans caliber for the test.

 

[cas6969]

Newton.......Are we talking about Newton?!?!?!?!??!?

And a cold glass of milk. Mmm...

 

[E. Bryant]

They kind of already do that, except maybe the slo-mo camera part. Benchrest rail gun competitions are fascinating.

So when I remove the human behind the recoil pad, the error goes away, and when I add the human back in, then we start missing targets. Tells me that an academic exercise on barrel wobulation ain't the priority.

Now, as an engineer, I do find the postulated hypothesis of barrel deflection/distortion plausible and fascinating. There's certainly enough force involved to move things around, these forces reach a peak shortly after start of combustion (when the bullet is barely moving), and we know the barrel moves before the bullet leaves the muzzle because things get screwy if the barrel is not properly floated or pre-loaded. Understanding the deflection would be the first step towards reducing it. But the shooter is still the problem.

 

[DeathBeforeDismount]

 

[Im2bent]

And a cold glass of milk. Mmm...

Dude Oreos for the win!