Well???Kudude

Velocity is a factor, but you can't go wrong with a 1:7, though a 1:8 will work and possibly a 1:9. I have a 1:7 and it does not have a down side that I can determine.

Since I don't know the length of the bullet, I can't apply the Greenhill formula:

T = (150 x (D x D))/L

T = rate of twist in inches
D = diameter of bullet in inches
L = length of bullet in inches

Jeff

Well, with the velocity up around 2700 fps or more, my Savage 12 BVSS seems to stabilize the Sierra, and Nosler 80 grain Match bullets just fine...

I am waiting to order some of the new 80 grain V maxes that Hornady is making...

I can see some serious long range varmint potential there....

I have a 22.250 that I had made on a Pac Nor barrel with a one in 7 twist...

It has no problems stabilizing ANY 80 grain bullet so far....and it sure likes to vaporize 50 and 55 grain SPSX bullets about 12 inches out of the barrel, at ANY velocity except real real low.. like 2000 fps or less...

Sierra's 80 gr. bullet is 1.080" long.
Hornady' 80 gr. bullet is 1.123' long.

The greenhill formula gives a fair approximation of the twist rate needed. However it does not account for velocity. This is why my 1 in 9" twist 223 with a "stiff" load will stabilize an 80 gr. Sierra bullet.

muck

Thank you all, very much. Kudude

AND A HAPPY THANKSGIVING TO ALL!!

This will tell you everything you want to know. It is much more accurate than Greenhill.

Depends on elevation, velocity, length and shape of the bullet. My 9 twist 223WSSM stabilizes 80 gr. Noslers just fine at 3300 fps and 5,000 ft of elevation. HTH, Dutch.

I am working with 7 twist barrels now , but 18" Long Range Pistols .. 223AI , 22-204AI , and soon 22x50R imp ...in Contenders . A 22-250AI in a 18" Encore Pistol ..
My Contenders have been shot to 1000 yrds ,about 11" groups so far...And PD's at 776
yds....

I just started testing 80 amax , and 90 gr sierras , would like to try "Wildcat" 90's
...Wildcat makes 100's also , but ,those will take a 6.5 twist I think..
Ray

Hello,
Shot a Krieger and Douglas 8 twist, 30" barrel for a lot of long range matches, 1000 yards, and both performed very well. Would hold X ring groups at that range or less than 10" in prone/sling shooting. Sierra is the only bullet most of us used in those days for such shooting. I found the cartridge/bullet/barrel length combination to pretty much duplicate the performance of the 308/155 Palma bullet. In short, you have to read the wind closely, but it does work. Good Luck

Lots of good contributions guys, plenty of food for thought. One other thing to consider - bullet consruction. Some bullets do not take kindly being driven over their recommended highest velocity. As a rule of thumb, most 80gr 224 bullets will easily be stabilised by a 1 in 9 twist rate. Some manufacturers such as berger recommend 1 in 8 for their products.