What rate of twist, and barrel brand for project.

[458Scout]

A little project I've been toying around with for a few years needs to be concluded.
I have a fair amount of 452's and 458's - so please no recommendations of other firearms.

The cartridge is my own design, and will be chambered in a Remington 700 SA as a single shot with a new bolt will be ordered from Pacific Tool.

Now I need to to consider type of barrel for best accuracy.
Barrel: 18" long in a medium - heavy contour.
Bullet: .458 hard cast weighing between 300 - 325 grains.
Velocity: 1708 f/s ( There is a reason for that, plus I like that number.)

Any experienced suggestions for the questions below is greatly appreciated.

1. What make.

2. Type of rifling cut.

3. Rate of twist, or any other suggestions

Thanks

[Artful]

What is the specifications on your custom cartridge?

[458Scout]

1.75" 458Win Mag

[Artful]

As your looking at trapdoor like speeds, I'd problably use 1-20 or 1-22 twist, I'm partial to deep cut Ballard rifling of even number for cast as opposed to poly or micro grooved - I assume you will be working without gas checks most of the time. As far as makers - there are so many good ones. I have barrels by Douglas, McGowen, Montana, Lothar Walther, Shaw - all work well - friends have Shilen, krieger, Lilja, Hart, Pac-Nor - and they all work well also.
here's a link to some others.
http://www.6mmbr.com/barrels.html

You going to try and do Sub-sonic as well with this cartridge? Are you thinking Paper Patched?

[DCM]

A twist calculator that works for all. http://castboolits.gunloads.com/showthread.php?107867-What-twist-rate&highlight=twist%20rate

[458Scout]

Took my Marlin 1895 GS to the range today with some 360 gr hard cast. Had a 6 km/hr west wind and minus 15. Very nice day.
Experimented with 4198, 3031 and RX7. The 4198 and 3031 were reduced probably to much. Maybe I should have used a filler as it seemed there was a hesitation between ignition and actual firing. I finally have the perfect load in cast with 39.0 grains RX7 and this particular bullet. Anyway this was been my last attempt at reduced loads. We'll see how it works on gophers this spring.

[725]

I'd look up the "Greenhill Formula" to guide you in your project for a rate of twist.

[smokemjoe]

My Wendrl has a 1-28 twist, It shoots the 330 gr. Gould bullet very good.