What would you recommend for a twist rate for the .450 Rigby and why?

1 in 14..... 1 in 16...?

I know you can shoot upto 600 grain bullets and want to cover all my bases.

Best,
Dave

1:12"

That way the number of revolutions per second of the bullet is numerically the same as the feet per second, muzzle velocity.
Different units, same number.

Seriously: No slower than 1:14".
1:12" gives an edge on stability with long monometals, and cannot hurt anything else, unless you plan on 1000-yard target shooting.

450 Rigby: Standard CIP twist is 1:420mm = 1:16.53"
460 WbyMag: Standard CIP twist is 1:406mm = 1: 15.98"

1:14" is standard on .458 WinMag and .458 Lott.

I chose 1:12" for a 460 Wby custom and a .458 Lapua Magnum.
Excellent. Absolutely no problems there, could not be happier, blah, blah, blah.

If you want to shoot 600gr bullets of conventional construction, take 1:12" twist. As RIP has said, tighter twist hurts nothing with the lighter bullets and is an advantage with the longer bullets.

I went with a 1-10" barrel, that works...

10 Is excellent. The tighter the twist is, the more versatile the rifle is. Whatever bullet is used, the gyroscopic stability increases as twist increases.

With monometal bullets, the transition from flight to tissue is improved and the bullet is less likely to veer in target. If distance is required, longer bullets with higher BC can be used.

Agreed. 1 in 10" to 1 in 14" - with the faster end of things being preferable only if you intend to shoot very heavy for caliber bullets.

quote:

RIP said:
. . . and a .458 Lapua Magnum

I didn't know that RIP did a 458 short Rigby. Congratulations.

Thank you 416 Tanzan, Re. .458/.338 Lapua Magnum:
That was my first Lapua wildcat about 10 years ago.

1:10" twist Big Bore rifles I own:
(All McGowen Precision!)

404 Jeffery x 2 rifles
.423/.416 Rigby Improved Plus
.458 B&M
470 Capstick
.505 Gibbs
500 A-Square
500 Mbogo

1:9" twist: 500 Mbogo, the second, with a Pac-Nor barrel.

1:12" twist:
"49/.500/.338LM Improved of 2010" aka 49-10 (aka 12.7 x 68 "Tornado" Magnum) x 2 rifles
(Both Pac-Nor.)

And so on, many-many-many 1:12" twist: .375, .416, .458 ...
One 470 Mbogo with 1:16" twist: I was young and foolish.

Never have had a problem with "too much twist."

Yes! 1:10" if you dare ... but I still am fond of RPS = FPS at the muzzle with a 1:12" twist.