What would the MPBR for a 6.5X55 with the 155-156 grain bullets be?

If you input the data, the JBM program will calculate it for you.

http://www.eskimo.com/~jbm/ballistics/traj_basic/traj_basic.html

ray

What muzzle velocity, sight height, and zero are you talking about? These are important variables necessary for an accurate calculation. For example in 6.5x55 a 160 gr Sierra@2400fps, a sight heigth of 1.5 inches, sighted 2 inches his at 100yds gives a zero of 175 yards. Take an average of an 8 innh kill zone the MPBR is 225 yds according to the Sierra balistic software. Change any of the variables and the results will change. This includes bullet type. I play around a lot with these calcualtions befrore I begin to load. It is IMHO interesting in addition to being a good predictor of performance. I then load for accuracy and after finding a satisfactory load I recheck the balistics calcualtions for MPBR. Sounds complicated but it really is not. The Sierra infinity Suite is available from MIdway and other at a very decent price for the value it provides.

Do those of you who use the MPBR factor group size into your calculations?

333_OKH,

If you go here Pointblank Software and download the software you can do as many calculations as you like.
Hope this helps,

John

nordrseta, yes, I consider group size, to a point. If the rifle is a 2" gun, and the MPBR is 300 yards, then I make sure that it is a 6" gun at 300 and then go from there. Even if the mid-point is 3" high at 200, then center of a 4" circle is 3" high, that will still kill cleanly, as will a 6" circle 3" low. But then I don't have any 2" rifles. That is where accurate rifles build confidence. If it is a 1" rifle and the rest is good and steady, that changes the ball game, distance wise.

I aim center forward chest anyway, not low and hope to hit the heart. I would just as soon have both lungs, or a shoulder as definite rather than a "could be" heart shot.

333-OKH, the Point Blank software is good.