Cool bbl vibration video.

[Harter66]

I saw this and thought it might make explaining bbl ''whip''easier . It is certainly obvious here.


https://www.youtube.com/watch?v=ozyw84Swmb4

[USAFrox]

Dang, that looks a lot more extreme than I ever realized it was. Unless that barrel is more flexible than the norm. I liked how that first case slowly ejected spinning right into the camera. Cool!

[prs]

Watch the damn fool bash his eye with the scope! Time after time after time! He uses almost zero eye relief. The scope is bending more than the barrel unless it is an optical artifact.

prs

[USAFrox]

Well, he does have one of those nifty rubber accordion bumpers (whatever you call 'me) on the end of the scope, but you're right about the scope flex. Never thought about that before. It's a wonder with all that movement that these things can still accurately put shots in the same vicinity.

[Harter66]

It looks like a 7.62x54R . I know an S k S pretty well (I know its an ak cousin) the bbl is skinnnny from the gas port out . Like .7 skinny for the last 12'' or more. Did you notice how much the gas port moved ? I was actually suprised by how ridgid the action stayed w/the bbl hopping all over.

[nighthunter]

Maybe just me but I'm very curious to know how much the flash suppresser effected the barrel and I'd like to see several shots from a different angle and slower speed to see if the projectile has exited the barrel before the majority of the barrel movement takes place. It is interesting to view this video but remember there is more than meets the eye here.

Nighthunter

[Dale in Louisiana]

Skinny barrel on those things. It adds to the flex.

It is well to remember that the Eastern Bloc's 'sniper' role is more akin to our 'designated marksman' role.

I have run into several owners of Eastern Bloc 'sniper rifles' who were surprised that a stupid ol' sixty year old Garand will ring the gong right alongside them all day, without the scope.

dale in Louisiana

[geargnasher]

MmmmHmmmm. Anyone loading for accuracy in any rifle should watch and ponder how they're going to build ammunition that launches a boolit so it exits the muzzle to exactly coincide with the same point in the wiggle every time. My gunsmith just informed me that my 24", .30-caliber bull barrel droops eleven thousandths under it's own weight, imagine how much it moves at 45K psi.

Gear

[Harter66]

Here's a shamless ad that has a heavy bbl AR that wags every bit as much.

http://www.youtube.com/watch?v=0Xr_RG_lcNk

[willie_pete]

That's why I use a ladder test for load development.

WP

[303Guy]

The trick is to not have the muzzle at a node - then it changes angle and points away from the bore line. If it moves parallel then its fine. I was playing around with a barrel vibration program and was astounded by the degree of movement and angle change predicted. Now I see it was right.

[popper]

Note all those videos are of guns with gas ports and the 'whip' is parallel to and after the port.

[geargnasher]

The gas blocks add weight to a point on the barrel, creating a secondary node ad the center of their inertia. Ever wonder why Mauser barrels have several diameter steps?

Gear

[MaryB]

PSL 54's are notorious for flexible barrels and poor accuracy after a couple shots.

[303Guy]

Ever wonder why Mauser barrels have several diameter steps?I heard it said the steps were to break the harmonics pattern that forms in a smooth taper barrel or something like that. Not sure what difference it actually made. That barrel vibration is why SMLE's had cork packed fore-ends.