Help with Bullet Grain Weight

[Shuttleman]

Veral, I have been shooting for years but not really paying much attention to the grain of bullet I was using more just grabbing a box at the sporting goods and headed to the range or field.  I have been shooting more and more over the past several years and now buy reloaded ammo from a reputable company offering different bullet weights.  So the question I have is there some table or way to better understand the right grain for the right application?  For example: for my 1894C in 357/38, the 357 comes reloaded in 125gr and 158gr.  So is there a simple rule of thumb on this or is it much more scientific.  A guy at the gun show this weekend told me that it’s based twist rate that dictates the grain based on how the bullet will stabilize (less twists indicates a heaver grain bullet and therefore with more twists a lighter grain bullet will stabilize better).  I also have the same dilemma with my 9mm 115gr or 124gr.??  99% of my shooting is at the range so I usually go with FMJ as it seems to leave less deposits in the barrel and easy cleanup.

Any help to enlighten me on this head scratching subject would be greatly appreciated.

Tom

[Veral]

  Twist rate of the gun of interest is only important to consider when choosing bullet weights which are heavier than the normal factory weight offerings.  For your 357 carbine you'll almost certainly get best accuracy with the heavier 158 gr, and 180 gr is best with LBT FN cast bullets.

  For the 9MM probably the heavier will be most accurate, but the weight defference is small and it may not show on target.  In both instances what I've reccomended is the bullest with most bearing length, which makes the traverse the bore most precisely. (Less tiping.)