I've been working with (read as pestering) Woody Woodall at Lothar-Walther for a .510" barrel for the last few (8 to be precise) months. They are constantly evaluating their barrel offerings and were updating certian selections, and the .510" barrel was one of them. Well, after a few delay's the shipment should be arriveing in 2 to 2.5 weeks. In the .510" department, there will be 40 coming in. Twenty of them are going to 'A' company and the other 20 (or whatever # haven't already been spoken for) are for the shelves. I am getting one for sure, but thought I'd let you guys know. The barrel spec's are:
Stainless Steel
28" long
1:10 twist
1.25" blanks (specify what contour you want)
Price is going to be around $220 - $240 each.

So if you're looking for a barrel for a .510" project call Woody @ 770-889-9998

That is one heck of a tight twist?

That is the twist that Art Alphin recommends for the 500 A-Square. He says that penetration is better with a fast twist. But of course that also pushes pressure a bit higher.

With a .510" bullet at slower (2000-2400fps) than a BMG (2700-3000fps) velocity, a faster twist barrel will stabalize bullets better.

As 500grains mentioned, Art Alphin recomends the 1:10 twist for the .500 A-Square (Also the .500 Jeffery & .495 A-Square). For the only other .510" round that is mentioned in the A-Square reloading manual 'Any Shot You Want', the 500 NE 3" shows a 1:15.
One also has to remember that the 500 NE 3" operates at much lower pressures (31,800 - 39,400) where the .500 A-Square has safe working pressures that are much higher (42,900 - 61,600).

The 1:15 twist is more in line with my experience, but I am more an old british calibre fan.
As far as getting better penetration with a faster twist, I will be happy to stay with my 1:15. This gives my 540gr solid @ 2180fps complete end to end penetration on a buff.
Hopefully I will never need more than that

It's a fact that J.D. Jones chose 1 in 10" for the 50 Peacekeeper, A. Alphin used the 1 in 10" twist with the 500 A2, and I have experience with two rifles ( 510/460 Weatherby Improved Jenkins and Berry ) that have the same fast twist: 1 in 10".

If you are just going to use the stubby 600 grain and less bullets, 1 in 15" is O.K.

If you want to have great accuracy with the BMG target bullets and great accuracy and penetration with the lighter hunting bullets, then the faster twist is the way to go, at the less-than-BMG velocities.

Then, instead of penetrating one buffalo or elephant end-to-end, you can perforate two with the same shot, end-to-end.

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Good huntin', shootin', and spear chuckin',
RAB

THE BARRELS ARE IN! THE BARRELS ARE IN!
Um, I mean, I've heard that some .510" barrels arrived at the Lothar-Walther facility in Georgia for those who are interested.