Twist rate for new .308 barrel

[jaysouth]

I am about to place an order for an Encore barrel in .308. It will shoot cast bullets from 150 to 185 gr. Do I want 1:10 or 1:12 twist rate?

Or, would I be better off with .307 with rimmed case? For cast bullet load pressures, would .30-40 work as well as .307/.308?

[John Taylor]

With the lower velocity of cast boolets I would recommend the 1 in 10 twist with the 185 grain. A 1 in 12 with the 150 should work. I was able to get great accuracy with 1 in 14 but that was a 300 mag on a 31" barrel shooting 180 grain Jacketed at 3,400 FPS.

[stubshaft]

I would order a 30/30 barrel as it is one of the best cast bullet cartridges ever developed. The 308 and 307 will have an excess of airspace and lower loading density, you will need more powder to equal the 30/30 velocities and will not gain too much more velocity. The longer neck of the 30/30 is also a plus.

[uscra112]

Another vote for .30-30. The only other .30 caliber worth a hoot with cast bullets is the Krag, but the extra powder space needs a long barrel to take advantage of it. NOTE: The standard .30-30 chamber has a rather abrupt leade. Reaming it to look like the .308 throat will do wonders. Outpost should chime in here - it was his article in the Rifleman that taught me this.

[Doughty]

What velocity range(s) are you wanting to shoot? It is much easier to find .308 Win than .30-40 Krag brass or ammo, however in a single shot I like the .30-40. I also find it much easier to get a .30-40 to perform like a .30-30 than it is to get a .30-30 to perform like .30-40. In a single shot that will handle a .308 Win, the .30-40 case can match or exceed the .308.

I have a Ruger #1 chambered in .30-40 with an 11.25 twist barrel. I like it, a lot.

[Larry Gibson]

Whichever cartridge get the 12" twist. It will stabilize a 311299 at sub-sonic velocities. Thus your 150 - 185 gr cast bullets will be no problem and on the top end you could get 2400 +/- fps with very good accuracy.....much easier to get accuracy above 1940 fps than with a 10" twist.

I've shot out my Ruger #3 22 Hornet and am considering a Jes rebore in 30 cal chambered in 30-30 with a 14" twist. That will very nicely stabilize my 311041 (178 gr at .988 length) down to 500 fps. Will be much better with lighter weight cast bullets too.

Not guestimating the above as I have .308Ws in 10, 12, 13 and 14" twists and have shot those bullets in those.

[GBertolet]

I have a 1-14 twist on my rebarreled 788 in 30-30. I bought a special reamer from Manson. Dimensions are tightened up for the throat, and has a 1.5 degree taper for the leade. Designed for cast bullets. Handles ok the 170 gr. 311291 bullet @ 1600 fps out to 200 yards. This is probably about the weight limit for this slow of twist, at typical cast bullet velocities. I have a Lee 150 gr bullet I like to use also. Shoots just as well, and uses less lead. Rings the gongs @ 100 yards, just the same. The 30-30, and 30-40 are ideal cartridges for cast bullets. The long necks of these cases are perfect for bullet retention and alignment.

[Larry Gibson]

Twist rate for bullet stability has nothing to do with bullet weight. The length of the bullet is the critical factor.

[GBertolet]

True, but weight is generally used as an approximate reference, although length is the ultimate demominator.