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Any Cal.
02-05-2013, 12:40 AM
Ok, I am playing with a 1:16 twist .429 and a 1:9.5 twist .40. How fast would I have to get a long bullet moving to stabilize it? Would anything over 600fps be fine because of the fast twist? Any rules of thumb? I would like to do some ultra heavy bullets, but want them to be very stable; I am thinking that these twists should be fast enough to stabilize almost anything up to 1 1/4" long or more, even at fairly low velocities.

Thoughts?
44man
02-05-2013, 09:25 AM
I don't know about the .40.
Do you have the Shorty BFR in .44? It is 1 in 16". It will take a little heavier boolit or say a 310 to 320 gr just a little slower then my Ruger will. I have a 10" barrel so the 6" barrel of the BFR might shoot the exact same loads. Mine run at about 1316 fps.
There is no rule of thumb that works and don't expect drastic changes and very low velocities. If you go to a 400 gr in the .44 you will still have trouble.
To take a guess, the 320 in a 1 in 16" might be 50 fps OR LESS then from a 1 in 20" and could be only 20 fps. No math on earth works, only the targets tell the story. 600 fps is barking at the moon when it is not up.
Larry Gibson
02-05-2013, 01:32 PM
There are several formulas for calculating stability (a search or google will easily find them) You already have the important parts (Twist and length of the bullet) Off the top of my head I'd say both will stabilize a bullet that long at 600 fps.

Larry Gibson
Any Cal.
02-05-2013, 02:56 PM
.44 is a Redhawk. 600fps was just a talking point, I am expecting at least 1000. It does 300g fine, just considering going heavier.

Found the nennstein-ruprecht.de site and learned some, they have the formulas when I get up the courage to tackle them.
44man
02-05-2013, 04:32 PM
.44 is a Redhawk. 600fps was just a talking point, I am expecting at least 1000. It does 300g fine, just considering going heavier.

Found the nennstein-ruprecht.de site and learned some, they have the formulas when I get up the courage to tackle them.
The .44 RH is 1 in 20". You will top out at about 330 gr. And velocity will be around 1300 fps or a little more. Heavy boolits do not do well slower. A 400 gr will make oblong holes at 50 yards.