Lets Assume You Are Building a 6"-10" 458 Win Mag Handgun ...

[Broc]

What twist rate would you go with on the barrel?

Bullets = 350gr plated Berry's

I was looking online, most forums say the 458 typically uses a 1:14, but some companies sell 1:20, 1:24. I checked the Winchester Model 70 and their rifle is 1:12.

But this is for a short barrel, so I need the smart people to tell me what is a good twist rate.

FAQ:
1. Broc, why? - Because I can.

 

[bfm]

FAQ:
1. Broc, why? - Because I can.

2. Rampaging Elephants.

 

[whatluck]

Shoot and cook your game at the same time!

I bet out of a pistol that 500 gr projectile will be moving at 357 mag speeds.

 

[Dennis in MA]

I htink something in teh size of a 6'10" bbl would be better. Just for recoil management.

 

[McReef]

First: Awesome!

Second: Twist Schmist. Will the projectile even spin, or will it just wind up your wrist as one might expect of an old Porky Pig episode? Would a smoothbore with a sabotted projectile be better suited (as on an M1 Abrams)?

Third: The science question is fascinating, and something I have pondered upon a bit myself for a very similar potential application. Basing this off of absolutely no knowledge whatsoever on the topic, desired twist would be calculated based on projectile dimensions, weight, and velocity right? Does the rifling in a barrel translate directly to rate of spin based on muzzle velocity, or is there slippage? (I don't mean to hijack, I just love a good puzzle.)

C: Awesome!

 

[Sweeney]

Go smooth bore with FSDS rounds.

But seriously... You'll need to calculate the muzzle velocity then determine the twist to attain the stabilization RPM for the projectiles you want to use.

 

[milktree]

Why does barrel length matter?

My understanding is that bullet length and diameter were the only relevant factors.

 

[45BPCR]

Want to buy a 45-70 contender?

 

[Stape]

You could set up an Encore in a pistol configuration easily enough. Order the barrel through MGM.

 

[Rockrivr1]

 

[Broc]

Shoot and cook your game at the same time!

I bet out of a pistol that 500 gr projectile will be moving at 357 mag speeds.

350 grain. Second line.

 

[Broc]

Want to buy a 45-70 contender?

I have an Encore, it is stronger than the Contender.

 

[Broc]

You could set up an Encore in a pistol configuration easily enough. Order the barrel through MGM.

That is exactly what I am doing.
I will order a custom barrel from Bullberry.

Next one will be a 458 LOTT.

 

[Stape]

That is exactly what I am doing.
I will order a custom barrel from Bullberry.

Next one will be a 458 LOTT.

You could go through SSK and have it magnaported and a TSOB mount installed. Both good ideas. Top quality one stop shopping.

 

[nm1]

That is exactly what I am doing.
I will order a custom barrel from Bullberry.

Next one will be a 458 LOTT.

You can shoot 458 WinMag from a 458 Lott chamber (one of the selling points of the Lott chamber)

 

[PatMcD]

The shorter the barrel, the faster the twist.

 

[Broc]

You can shoot 458 WinMag from a 458 Lott chamber (one of the selling points of the Lott chamber)

I didn't know that.

 

[chris_1001]

I’m so IN to shoot it!!!

 

[Broc]

I’m so IN to shoot it!!!

It is happening.

I will look at barrels this weekend.

 

[chris_1001]

It is happening.

I will look at barrels this weekend.

I can’t wait for your .50 bmg pistol!

 

[whatluck]

350 grain. Second line.

Wouldn't you have to run a completely different powder to get this to work? Seems like 90% of the powder would be unburnt in so short a barrel. Aren't .458 guns usually 24"+?

 

[Broc]

Wouldn't you have to run a completely different powder to get this to work? Seems like 90% of the powder would be unburnt in so short a barrel. Aren't .458 guns usually 24"+?

I don't know. 350 is what I reload for my 458 rifle so I figured I will shoot the same load.

 

[gerrycaruso]

What PatMcD said.

 

[cpgeneration]

Better be looking around for a wheel kit for it !!!

 

[gerrycaruso]

Hurry up and build it before you get too old to shoot it. I used to enjoy shooting 500 and 12 gauge handguns but not so much now that I'm old and weak. If you live long enough to get old, your reward is everything turns to shit.

 

[KMM696]

MGM lists either 1-10" or 1-20" in that caliber, Bullberry just 1-20". Bullberry likes phone calls, I talked to them 3 or 4 times in the course of a pretty vanilla 17 HMR barrel order - why not ask them? Bet they've done something like this more than once.

No complaints at all about Bullberry's barrels, that 17HMR they built me is the most accurate 17HMR I own. I did have to hand fit the barrel lugs to my Contender, but I'd much rather do that than have a loose lockup.

 

[milktree]

The shorter the barrel, the faster the twist.

Why?

Ruger Security-Six with a 4" barrel has a 1:18.75 twist, Marlin 1894C with an 18" barrel (same caliber, both .357 Mag.) is 1:16

 

[gerrycaruso]

I'm sure there are exceptions depending on powder choice but generally the shorter the barrel the lower the velocity. Stability depends on rpm and the lower the velocity the lower the rpm. Hence the need for a faster twist. I'm far from a ballistician but that's how I understand it.

 

[Chantry]

Why are you trying to make an orthopedic doctor rich?

 

[PatMcD]

Why?

Ruger Security-Six with a 4" barrel has a 1:18.75 twist, Marlin 1894C with an 18" barrel (same caliber, both .357 Mag.) is 1:16

I have no idea why your 2 examples have the same twist; I don't play with those.

Think of it this way: once the the gun is fired and bullet is on it's way, it doesn't start twisting immediately. There's a little "skip" until it fully engages the rifling. Let's use the example of the 223, because that's what I'm most familiar with. A 26" 1-8 twist will reliably shoot 82 Bergers. A 20" barrel wants a 1-7 to shoot the same bullet. What? Because it's possible the shorter barrel hasn't imparted its full twist to the bullet. The 26", because it's longer, and the bullet is in the barrel longer, has time to get that complete 1-8 twist.
Now compound that by comparing a 20" rifle barrel to a 10" pistol barrel.

We're taking about pure, theoretical accuracy here, and extremely small degrees of difference.
Sound like bullshit? Probably is. But that's how it was told to me by someone who earns a living doing "barrel stuff".