Barrel whip?

[lazyeiger]

What causes barrel whip? see the video below of savage 308 TA with Lilja medium Palma barrel 32" long. I have never seen any other rifles do this. I am not sure if it effects accuracy but it certainly is very unnerving for me and makes it very difficult to shoot consistently. Since the video was taken I have shortened the barrel to 30" and there is no difference in the barrel whip.

Thanks

Jon


[youtube]http://www.youtube.com/watch?v=z_eFnkPWpyY[/youtube]

 

[chino1969]

Every barrel whips to some degree. Look at slow motion video of 155mm Howitzers or Abrams tanks and you'll see barrel whip.

 

[spclark]

ALL barrels "whip," some more than others; it's a function of vibration nodes.

That's why barrel tuners are popular as a means to "time" the whip to coincide with the moment a bullet is clearing the muzzle. Idea being to have that moment when the muzzle itself is not moving, either top or bottom of the cycle.

Also big, fat heavy "Bull" barrels where practical, and the practice of "free-floating" barrels so they don't encounter resistance to movement when in a vibrating state.

 

[Laurie]

Even .22LR barrels vibrate hence the popularity of barrel tuners in rimfire bech rest rifles. The more powerful the cartridge and the thinner the barrel, the greater the amplitude.

 

[markm87]

What causes barrel whip?

Tens of thousands of pounds of pressure pushing a bullet down a barrel would be my guess. 8)

The Ak-47 high speed videos are the best barrel whippers. Looks like a noodle flopping around when that thing fires.

 

[habu]

it's called 'random barrel oscillation' and can cause sever accuracy problems. one gent mentioned a 155mm how.. the original m109 SP how didn't have that much due to a short bbl. the later models - as in 'paladin' have a long bbl and can suffer RBO. - THE LONGER THE BBL, WITHOUT CORRESPONDING BBL DIA., THE MORE RBO.

the old m107 - 175mm - with 30+ft bbl had BAD 'RBO' at max. range - 32,000m - causing a 'range proable error' of 1500m!

that's why you see f-open shooter [because of weight limits] using full 1.25" dia bbl. - stability

habu
old arty man. ;D

 

[lazyeiger]

I understand that all barrels flex and the importance of barrel time to get the bullet to exit at a null point. It just seems that my barrel flexes more tan any other I have seen, either athe range or on you tube videos. It is so bad that I cannot use a shade on the barrel I tried velcro and it just flys off, then I tried tie wraps and it broke them. I cannot hold the target in the scope at all as the bipod jumps up and down all over the place. I could shorten the barrel more?

 

[markm87]

WOW! I didn't watch the video the first time I posted. I thought you were just asking a general question.

My Lord... I'd like to see that barrel shot with a high speed camera. The thing looks like a diving board.

 

[BoydAllen]

Just for giggles, try shooting it off of a standard front rest and see what happens. While you are at it, experiment with moving the front bag progressively farther back for each shot, till you are 2-3 inches in front of the action. Obviously this will entail holding the rifle, which you are probably already doing. If this solves the problem, I would think about having an accessory rail installed on the bottom of the forend, so that you can mount the bipod in any position that you like, with a suitable adapter. Are you preloading the bipod legs?

 

[lazyeiger]

Thanks Boyd, some good ideas to try, I did shoot it off a rest in the front position and it was just as bad. I will try moving the rest back and see if that helps. It is a Sinclair bipod so I am not sure how to preload it as it just slides. I am almost at a point where I will get a new bull barrel as this whole thing is just frustrating me and making it almost impossible to shoot! I am also getting tired of this whole recoil thing and thinking of going for a 6mm br or 6mm x 47! as I mostly only shoot 600 yard F Class.

 

[rain164845]

How good is your bedding? I think I would start there.

 

[K22]

You may want to try a barrel reasonator made by Limsaver. They are inexpensive and are adjustable so you can find the "sweet spot" in your barrel's harmonics. I used one and it reduced my group size about 40%.

My gunsmith told me that short (20" to 22") "heavy" barrels have the best potential to shot accurately since harmonic are more stable. He rebarrels a lot of benchrest rifles.

 

[BoydAllen]

That bedding suggestion got me to thinkin'. Grab the barrel in one hand and the fore stock in the other and try to pull them apart and then push them together to see if you get any unusual movement. . If you had a pillar come loose in the stock, the action screw would still tighten, but the action would not be properly secured.

 

[lazyeiger]

it is bedded using a whidden v block I have checked and double checked and cannot find anything wrong.

 

[CJ6]

For a better uderstanding of BBL whip go to Varmit Al's web site.......

 

[lazyeiger]

I think I understand barrel whip I just don't understand why the whip on my barrel is so much more than anything else I (or many other people at my ranage) have ever seen.

Is it possible that the way the barrel was chambered could cause it? I did all the metal work on this rifle my self. Even though I am an experienced machinist (not by trade) this is the first chamber I have ever cut.

 

[CJ6]

Barrel contour and length

 

[lazyeiger]

Barrel contour and length

Yes at first look these would seem to be the only variables. I have a collegue that has the exact same barrel contour and length from the same manuafcturer (Lilja) also using the same action (Savage TA). His rifle doen't exhibit the same barrel whip, in fact it is almost undetectable with the naked eye. I have shot his rifle and it is a lamb compared to mine????