Rate of Twist .270

[JerryM]

I have a friend in Africa who is planning to build a .270 cal rifle and will use the 130 gr Barnes X bullet exclusively. He has asked that the following question be posted :
What is the absolute slowest twist that will stabilize the 130 gr Barnes X bullet, OAL 1.185",at a velocity of 2500 fps, at a max range of 250 yds? His purpose in wanting that velocity stems from the fact that the Barnes X bullet petals expand more at the lower velocities. That surprises me somewhat, but he has dissected hundreds of animals over the past several years through both safari and culling experience. I realize this is a difficult question and maybe no one has a good answer, even with a good computer program. Thanks, Jerry

 

[Mal H]

JerryM - I apologize in advance for asking this, but I gotta. Why is he "building" a .270 when so many fine rifles already exist in this caliber? And a 130 gr bullet at 2500 fps? Sounds like the worlds first "tamecat" load. Are you sure he is in Africa?

 

[JerryM]

Mal, Your apology is accepted. Yes he is in Zimbabwe, and has been there since he retired several years ago. He is a savy gun nut. His shots are normally within 100 yds. He has found that at these short ranges 2400-2500 fps seems to be the ideal velocity for the best bullet performance. As I said, he has determined that by dissecting hundreds of animals. He uses the Barnes X now I think exclusively for soft skin game. He is aware of all the good cartridges available, but just wants to play with this I guess. Who knows why some of us want a wildcat when anything most could want or use is available. At any rate he does and although he has a computer program, he believes that the program specifies too fast a twist. I doubt that anyone has a very accurate answer to his question, but all I can do is ask, and see if we have a physics professor that is interested in ballistics. Best I can answer. Jerry