223 12twist heaviest bullet?
 

i heard through the grape vine that i shouldn't get a 69gr with a 12 twist. is this true....what is the heaviest i should go.

i ordered some 69g siera's? bthp? in 223. whats the length difference? per say my 55g remi corelocks

The bearing surface on the 69's BTHP is going to be much less per grain of weight than with the 55. You will have to push them pretty hard to get the velocity up enough to offset the lost stabilization with the heavier, less bearing bullet. I am not sure there is enough room to do it with the case and a 1/12 twist. With normal loads, the 69 is just not going to be able to spin fast enough to stabilize completely.

I hope that makes sense, at least thats the way I understand it.

Later,

Marcial

The heaviest I've ever shot in mine are 55 gr. V-max. They are very accurate in my 1-12.

You won't get a 69 grain SMK to stabilize at .223 velocities in a 12 twist barrel.

A 55-gr Remington measures 0.619", while the 69-gr SMK measures 0.895". The key is not the length alone, it's how much of that length is in contact with the rifling, as has been mentioned already.

I'd like to hear how bearing surface of a particular bullet effects how fast a bullet is spun as it travels down the barrel.

makes sense to me..the more surface friction, the more it slows. how much, i have no idea.
since your asking..i imagine bearing surface is the part that dont touch the rifling?

what rpm ya lookin fer?

There is only one real way to know how a particular bullet will fly in any particular barrel or twist rate. And that is too shoot it. Then you will know.

Yes there are general rules of thumb with twist rate and bullet weight, and bullet length. And those are great recommendations to follow.

However the bottom line is you never know until you try it in any particular rifle.

I have seen heavy bullets stabilize in 1in14 Remington's. And I have seen 50 grain bullets stabilize and shoot bug holes out of my 1in8 twist Krieger. That same Krieger also shoots bug holes with the 75 grain A-Max bullet.

What the guys have said above is a good rule of thumb. But I have seen tons of rifles that do not shoot to the "rule of thumb". So just try it if you already own the rifle. And if you are building or buying a rifle then try to buy the closest twist to the bullets you wish to shoot.

But nothing trumps just getting out there and trying it!! Tom.