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1:10 vs 1:12 .308 Which is better all around(er)
- Thread starter deepcore
- Start date
whether a bullet will stabilize with a particular twist depends on 4 things 1) length of the bullet 2)Diameter of the bullet 3) velocity of the bullet 4) specific gravity of the bullet.
Here is a online calculator which uses the Miller formula that should help you out assuming you know basically what bullet you will be loading and the appx velocity you can expect if you have a bullet to out a mike on. manufactures are not exactly free with that data and the easiest way would be to find a box an measure them. Play with it a bit and you will see that the lower the velocity the shorter the bullet has to be for the same barrel twist.
http://kwk.us/twist.html
using a .308 Berger 155.5 Palma bullet which is 1.4 inches long and which I shoot at 2775 I am good to go with my 1:12 barrel
Now to confuse matters even more the shape of the bullet affects the length. A 155 Gr SMK is 1.202 inches long because it uses a tangent ogive rather than a secant + tangent hybrid profile like the Berger. BTW the SMK's shoot just as well if not better in my gun than the higher priced Bergers do. A buddies same brand/model gun is just the opposite and loves the Bergers
if you want to know the hows and whys and want to get a math headache then this read this
http://www.jbmballistics.com/ballistics/bibliography/articles/miller_stability_2.pdf
but the bottom line is this, forget the math and get whichever gun you like the best and play with some bullets and powders to get the accuracy the gun likes the best. What do you plan on using the gun for varmints in N Dakota or deer hunting in Tennessee. Get the one that you would be happiest with, If you want to use it for LR then 1:12 155's will do you just fine, that is a s heavy as the 1000 yard Palma shooters are allowed.
Here is a online calculator which uses the Miller formula that should help you out assuming you know basically what bullet you will be loading and the appx velocity you can expect if you have a bullet to out a mike on. manufactures are not exactly free with that data and the easiest way would be to find a box an measure them. Play with it a bit and you will see that the lower the velocity the shorter the bullet has to be for the same barrel twist.
http://kwk.us/twist.html
using a .308 Berger 155.5 Palma bullet which is 1.4 inches long and which I shoot at 2775 I am good to go with my 1:12 barrel
Now to confuse matters even more the shape of the bullet affects the length. A 155 Gr SMK is 1.202 inches long because it uses a tangent ogive rather than a secant + tangent hybrid profile like the Berger. BTW the SMK's shoot just as well if not better in my gun than the higher priced Bergers do. A buddies same brand/model gun is just the opposite and loves the Bergers
if you want to know the hows and whys and want to get a math headache then this read this
http://www.jbmballistics.com/ballistics/bibliography/articles/miller_stability_2.pdf
but the bottom line is this, forget the math and get whichever gun you like the best and play with some bullets and powders to get the accuracy the gun likes the best. What do you plan on using the gun for varmints in N Dakota or deer hunting in Tennessee. Get the one that you would be happiest with, If you want to use it for LR then 1:12 155's will do you just fine, that is a s heavy as the 1000 yard Palma shooters are allowed.
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I shoot my match M1A with a 1:12". This gets me 125's at short range (200yds) and 155/168/175's the rest of the way to 600yds. The M1A isn't as flexible with velocities, but for a bolt gun, I'd go with a 1:11 or 1:12.
I'd go with a 1:10" if I had a regular need for 180+grs. For daily use, I think the slower twists are much more versatile.
I'd go with a 1:10" if I had a regular need for 180+grs. For daily use, I think the slower twists are much more versatile.
The OP said all around jack of all trades 147 to 175 . To me this means long range hunting is on the table also. A 20 inch in 1-10 is going to be great for humping around the woods and takeing Deer and elk at range. As far as punching paper a 20 inch in a 1-10 is fantastic for 168 and 175,178 SMK or Amax .