.223 Bator mold RPM threshold

[vader]

Pretty much like the title reads----What is the RPM threshold for a 55 grain WW air cooled boolit? I have read that for the 30 cal its 140,000 RPM max but is it the same for the little 22 bator? Faster? (I hope?)

ANY discussion on the RPM threshold would be welcome! :)

Please chime in Larry Gibson!

Thanks in advance
Vader

[EDG]

Just guessing based on text book physics here but the rpm should increase by about 2X.
Centrifugal force changes by the square of the radius.

A. (.308/2)^2 = .023716
B. (.224/2)^2 = .012544

Then .023716 / .012544 ~ 2 or about 280,000 RPM but that can be affected by the surface texture of the bore and a few other things.

So the RPM would be about twice the .308.

The actual velocity will be affected by the twist.
A 14" twist .222 might work better than a 7" twist .223.

Work better means less RPMs per foot per second - at least until you get blow by or some other failure.

All of this assumes your 140,000 RPM number is correct.

[leftiye]

Horse feathers.

[rhead]

The outside edge of a 22 cal. boolit will be moving slower than the outside edge of a 44 cal boolit. So the structural integrity of the smaller boolit SHOULD withstand a higher RPM. This is not the only factor that effects the load. I do not know if the relationship between surface speed and boolit failure is linear.

[Garyshome]

Horse feathers. Welll not as best as i can tell! I guess when a 223 looks like #6 shot after it hits the target it might be spinning a little to quickly. Kind of the OLD method for getting things figgired out?

[Larry Gibson]

The RPM Threshold has nothing to do with surface tension. It has to do with how the centrifugal force affects the imbalances in the bullet.

The RPM Threshold for the bator .22 bullet of a ternary alloy normally lubed & GC'd will be between 120-140,000 RPM.

Larry Gibson

[EDG]

Formula for centrifugal force. F= mv^2/r

It is very difficult to argue with Sir Issac Newton. His laws have stood the test of time since 1687.

http://www.engineeringtoolbox.com/centripetal-acceleration-d_1285.html