PDA

View Full Version : Over Rotation



Twud
12-25-2007, 08:49 AM
Is it possible to spin a bullet so fast that accuracy suffers. Say a 40 grain 224 out of a 22-250 with a 1/8 twist at 3900 fps. Let's assume we're talking about a bullet that is not going to self destruct.

PEI Rob
12-25-2007, 10:43 AM
A bullet leaving a barrel is not perfectly balanced, albeit very close but there is no such thing as perfect. Since the imbalance is very small, spinning it at insane speeds opens the group up a tiny bit, but that is definately enough to make BR shooters notice. A hunter probably wouldn't notice the difference at a BR level but should be able to with regular gear. Of course you will have to try it and see, the result may not be that bad. Why not 4100+ fps?

Cheers,
Rob

mc223
12-26-2007, 01:33 AM
http://anarchangel.blogspot.com/2007/01/stabilization-mythology.html

J. Valentine
01-02-2008, 04:47 AM
Yes it is possible.
Bullets have manufacturing faults that affect balance.
Some custom made and target bullets are made to a high concentricity and very well ballanced . Some standard bullets are not so well balanced.
The effect is similar to an unbalanced car wheel.
At a certain speed it is not too bad but as speed increases the shaking gets worse until at some higher speed it is out of control.
An over stabalised bullet will suffer from increased precession ( Wind Roll ).
An over stabilised bullet with poor concentricity will be less accurate than the same bullet used in a slower twist.
I have found that a slightly slower twist barrel was more accurate at short ranges than the usual recommended twist for the same suitable bullet.

alinwa
01-02-2008, 09:51 AM
hmmmm, I'm impressed mc223...........the blog cited was pretty much spot-on, rare these days. There was a little bit about de-stabilization that didn't agree with my own experience but generally good stuff... :)


nicely done


al

mc223
01-02-2008, 02:22 PM
Al, did you follow any of the links to the other articles? The 1 about terminal tumbling is also interesting.

alinwa
01-03-2008, 11:20 PM
mc223,


Nawww, ran outta' time, I'll tag it tho


thanx


al

John S
01-04-2008, 12:08 PM
Possible yes.

If you want to spin them fast you will need a quality bullet.

bd1
01-04-2008, 06:32 PM
The answer's clearly yes. A few years back we loaded up some 40+ grain varmint bullets in .223 cases pretty hot, shot 'em with our 7-8 twist AR DCM-type service rifles, partly for grins, partly to see whether the bullets would hold together at 200 yds. Most of them vaporized about 100 yds downrange.