.243 vmax bullets/rpm limits

[Lapuatom]

Recently purchased a Weatherby mod 307 in .243. It has a 7.5 tw and I was wondering how much spin a vmax bullet can take before they give up the ghost?

 

[dirtytough]

Supposedly 300,000 rpm's. So like 3125 fps out of a 7.5 twist.

I have heard of people shooting them with a lot more RPM's then that though.

 

[Black Hat]

With that twist rate I'd be aiming heaver than 87 grain, something like 105 VLD.

 

[Tiny Tim]

The vmax may or may not come apart at that twist rate and speed. It's one thing to do it with a new, and hopefully smooth, fresh barrel. As the throat becomes rough and fire cracked, it likely won't hold up. I recently had this discussion with Bartlien Barrels on an order I was placing for a 6 Max

 

[lancetkenyon]

I can tell you this.

I did the testing for the very first 6SST.
26" 1:7" Brux 5R
A 6mm 85 VMax WILL vaporize at 3450fps. 355,000 rpm

It was pretty cool to witness.

 

[Tiny Tim]

I can tell you this.

I did the testing for the very first 6SST.
26" 1:7" Brux 5R
A 6mm 85 VMax WILL vaporize at 3450fps. 355,000 rpm

It was pretty cool to witness.

I bet!

 

[K.E.C.]

One of the ways to figure it out.

 

[dogz]

The vmax may or may not come apart at that twist rate and speed. It's one thing to do it with a new, and hopefully smooth, fresh barrel. As the throat becomes rough and fire cracked, it likely won't hold up. I recently had this discussion with Bartlien Barrels on an order I was placing for a 6 Max

This...........it all has to do with how smooth or rough the bore is

Personally, I'd be all over the 70 NBT. Used to run it a lot in a 6/06, it was a wicked killer of small and big game

 

[Black Hat]

One of the ways to figure it out.

So in this case 307,200rpm with a 85Vmax @3200fps, should be fine but I doubt it's optimal for that BC.
If blistering speed with light projectiles is your game, a 1:9 twist would be a better choice, I've found twist rate can affect accuracy if it doesn't match the projectile.

 

[Lapuatom]

We ended up running 87 vmax @ 3250 without issues. Running 87 gr Absolute Hammer @ 3400. Rifle is a sub inch gun, nice hunting rifle.

 

[Dvldad]

I'm running 58gr vmax just under 3800 out of a 1-8 and have never had a problem

 

[Lapuatom]

That's a bomb waiting to go off!

 

[Airedale56]

Lapuatom,

According to the formula, I've run a 58 grain VMax in a Wby Accumark ULW .243 Win 1/10 twist 24" at 280,000+ rpm @3900 fps for over 25 years on coyotes. The bullet never came apart before impact.

Running the same load in a WBY 307 Range XP . 243 Win 1/7.5 twist 22" at 369,000+ rpm @3850fps still isn't vaporizing the bullet, before it gets to paper at least.


Looking for a wolf to test Berger 108 Elite Hunters on….

 

[M1A1ABRAMS]

One of the ways to figure it out.

Can I acquire to what book that is ?