First Build - Looking for thoughts...

[JJMoody]

Even a 9 twist will do you right. running a hammer, I'd run the 143s in a 280 ai. It'd be a good balance for speed and killin stuff. You can also run up to a 180 class bullet if so inclined. In my 28 nosler, and my wife's 280, I run 143HHs and 180 Bergers. It is an 8 twist, but a 9 would be sufficient.

 

[WahooYahoo]

A 1-9 up to a 180 Berger at 2950 and sea level is 1.53. Plenty for any hunting gun.
Why spin a bullet any faster than need be.

Free stability

 

[L.Sherm]

Nothings free, you just start putting stress on the jacket and loss velocity after what's necessary.

 

[WahooYahoo]

Nothings free, you just start putting stress on the jacket and loss velocity after what's necessary.

Granted. If you exaggerate anything you'll get to the other side of benefit. 8 twist over 9 twist is nearly free stability at the cost of 7fps, the increase in BC from .777 to .810 is significant (reference Nathan Foster)

 

[WahooYahoo]

https://precisionrifleblog.com/2019/06/30/personalized-drag-models-the-final-frontier-in-ballistics/

 

[L.Sherm]

Granted. If you exaggerate anything you'll get to the other side of benefit. 8 twist over 9 twist is nearly free stability at the cost of 7fps, the increase in BC from .777 to .810 is significant (reference Nathan Foster)

Accuracy trumps everything even B.C.

 

[WahooYahoo]

OK

 

[Lee Goodwin]

I would like a 28 Nosler. You would need a larger bolt head..?

 

[FIGJAM]

Granted. If you exaggerate anything you'll get to the other side of benefit. 8 twist over 9 twist is nearly free stability at the cost of 7fps, the increase in BC from .777 to .810 is significant (reference Nathan Foster)

Ok - so educate me on this...if I spin a bullet faster than I need to I sacrifice some velocity but gain in BC? Does it have an adverse impact on accuracy potentially?

 

[MudRunner2005]

I would like a 28 Nosler. You would need a larger bolt head..?

Yes, plus a fair bit more modifications to the rifle. The .28 Nosler is based on the RUM cartridges, which are based on the .404 Jeffery case. Significantly fatter in diameter than the standard bolt face (.473") cartridges like the .25-06, .270 Win, .30-06, .308 Win, etc...

He would have to have the feed rails on the bottom of the action opened up with a milling machine, and would have to swap his mag box and follower to a RUM mag box and follower, and open his bolt face up to a magnum bolt face. All this work will need to be done by a professional gunsmith.

 

[FIGJAM]

I would like a 28 Nosler. You would need a larger bolt head..?

I looked at the 28, but I would have to get a magnum bolt face.

 

[MudRunner2005]

Ok - so educate me on this...if I spin a bullet faster than I need to I sacrifice some velocity but gain in BC?

Essentially, yes.

 

[FIGJAM]

Essentially, yes.

Accuracy issues doing this?

 

[MudRunner2005]

Accuracy issues doing this?

It can. Over-spinning a bullet can sometimes cause detrimental outcomes, like bullet deformation, spinning the jacket off the lead core, and bullets essentially grenading in mid-air a few yards after exiting the muzzle. However, running a 7mm with a 1:8 twist instead of a 1:9 twist will not cause any issues at all, and will give greater stability, and will open up your abilities to run the full gamut of 7mm bullets.

Example, trying to run a 1:6 twist on a .257 Wby (at those velocities) can cause some issues.