Twist rate + 458 Lott

[Andrew NOLA]

I am considering rebarreling a 458 WM to 458 Lott. I would use primarily 450 and 500 grain copper bullets in it - Barnes TSX and North Forth Cup point solids

I know they come in 14 twist but I am considering a 12 twist Lilja for the longer copper bullets to help with stabilization and accuracy.

10 twist is also available.

What have others tried and what were the results?

Thanks very much

 

[USMA84DAB]

Art Alphin spec'ed the .495 A-Square at 1:10. The higher the spin, the more momentum to remain stable/the more difficult it is to de-stabilize the bullet as it penetrates. He was convinced that the higher spin rate would get straighter penetration/less propensity to curve off the line of penetration.

 

[Andrew NOLA]

I have found some more articles on here (Thanks, Micheal458). In the light of day, it seems that going from 458WM to 458 Lott today is not really much gain.

I might revisit this but am going to work on handloads and see what results I will get with the WM. I would like a faster twist exactly for the reasons stated above, but dont know that the squeeze would be worth the juice

 

[Hunter4752001]

If you're set on using monos then going with Lott is a better answer. The all copper projectiles are much longer than equivalent weight and therefore take up much more space in the case.

As far as twist rate goes I don't think you'll have a problem with the standard 1:14" twist. I use 450g monos and have no issues with stability. However if you need reassurance, get the specs for the projectiles you want and put them into any of the stability calculaors available on-line.

 

[skydiver386]

To much is better for stability than not enough, both for accuracy and terminal penetration when the bullets strike flesh. The standard 1/14 twist is fine for lead core bullets, but I think a faster twist is nearly always better for Barnes X and other mono bullets. I'd go with the 1/12.

 

[cajunchefray]

I have found some more articles on here (Thanks, Micheal458). In the light of day, it seems that going from 458WM to 458 Lott today is not really much gain.

I might revisit this but am going to work on handloads and see what results I will get with the WM. I would like a faster twist exactly for the reasons stated above, but dont know that the squeeze would be worth the juice

Pierre van der Walt has a nice discussion about twists rates and terminal performance in his book , African Dangerous Game Cartridges. Faster twist rate is better for terminal performance.
I conjecture that is one reason that the 416 Taylor, with 1:10 twist rate was considered effective.

The physical science he explains is detailed, but the concept is simple, run the drill bit faster and easier to get a straight hole.

 

[Nhoro]

I have a 458 win mag reamed to Lott and use Peregrine copper 515 gr solids and softs. No problems with stability. That is in a standard CZ 550. The Lott case allows me a bit more space and a larger variety of powder because of it. But I have used the win mag cases with bullets loaded out to longer OAL. The monometal bullets allow it quite easily with their driving bands.in addition, the 450 gr bullets are excellent in THE win mag. No real need to re barrel for faster twist or any real née for more penetration than you already get. They already penetrate more than the Nitro Express calibres of old.

 

[Riflecrank]

I am considering rebarreling a 458 WM to 458 Lott. I would use primarily 450 and 500 grain copper bullets in it - Barnes TSX and North Forth Cup point solids

I know they come in 14 twist but I am considering a 12 twist Lilja for the longer copper bullets to help with stabilization and accuracy.

10 twist is also available.

What have others tried and what were the results?

Thanks very much

10" twist RH is the SAAMI standard for the .458 Lott
with stated approval for anything from 10" to 20" RH or LH as optional twist rates.

Most factory .458 Lott rifles come with 1:14" twist, like the Ruger RSM.
So successful on the .458 WIN MAG, so why not ?

No need to rebarrel a .458 WIN MAG to .458 Lott.
But, if you are really stuck on the need for a SAAMI .458 Lottight rifle,
you will need a virgin barrel or have to set back the SAAMI .458 WIN MAG barrel.
This will allow the shorter cutting length of the SAAMI .458 Lott reamer to create the short and tight SAAMI .458 Lott throat.

Otherwise running a SAAMI .458 Lott reamer into a SAAMI .458 WIN MAG chamber will leave the terminal .458 WIN MAG throat blending perfectly into a leade-only throat at the chamber case mouth for a .458 Lott.
The SAAMI .458 Lott chamber reamer will perfectly clean up the SAAMI .458 WIN MAG chamber up to that new, leade-only throat.
The result is a .458 Lott Improved, like Jack Lott originally built, in 1971.
He used a .450 Watts Magnum chamber reamer with non-cutting throat beyond the 2.870" chamber length, in a SAAMI .458 WIN MAG rifle.
Yes, Jack's first .458 Lott accepted brass up to 2.850" long and allowed for case stretching on firing, out to 2.870" from breech face.
Eventually it was standardized on 2.800" brass length and handicapped by short, tight throat by Art Alphin/SAAMI.

Twist rate:
My .458 WIN MAG rifles (13 of them) have 1:10 or 1:14".
There is no significant difference in any of them, regarding apparent chamber pressure and muzzle velocity relationships or accuracy,
though the faster twist might be worse for cast lead bullet accuracy.

I have one .458 Lott Improved on a re-chambered Whitworth .458 WIN MAG, 1:14" twist.
and one SAAMI .458 Lott Ruger M77 MkII RSM, 1:14" twist.
My .458 Lott Ruger No. 1 got re-chambered to .450 NE 3-1/4".

The .458 Lott Improved is safe with .458 WIN MAGA handloads in 2.5" brass.
Those same loads are excessive in the SAAMI .458 Lottight, whether using 2.8" brass or 2.5" brass.

 

[Andrew NOLA]

I solved my dilemma by buying 3 458 Lott rifles. I really, really, really need to stay off of this site.

I am going to rebarrel one of those Lott rifles, still keeping it as a Lott, because I want to thread the end of the barrel for a suppressor and go with a 22 inch barrel, but don't want to ruin the factory barrel

So the question now is what's the best twist rate for a Lott shooting long copper bullets for best accuracy and penetration.

I am veering towards 12 twist. Long bullets plus the faster revolutions might help with penetration. Sort of like a drill bit spinning faster.

 

[Luvthunt]

Do not over think it, is it really going to matter at 50 yds or less to the buff?

 

[Andrew NOLA]

good advice that I wish my OCD would let me take