Nosler Partitions grouping right

[Rol Page]

Loading Nosler 180 Partitions and Sierra 180 BTSP in my 30-06 with 55.0gr IMR 4350.  They are both grouping, but the Noslers are about 1" higher and 6" right of the Sierra group.  The difference in elevation is to be expected due to velocity variation, but how do I account for the horizontal disparity?
I have some flat base Sierra 180's and will be trying them next to see if the boattail is creating the difference.  Anybody had similar results, and if so, what did you find as the cause?
Thanks in advance.   Rol

[necchi]

Well your velocity issue is part of the horizontal too, velocity effects rotation as well as forword momentum and Two other things;
*The bullet/bore contact areas, and profile of the bullets in question are different.
(sectional density(?)) These things can effect the barrel harmonics and recoil.
 
*Different alloy`s are used by each manufacturer, each has it's own drag ratio.
 
Suffice to say what your seeing is typical. It's hard to get two different bullets by the same maker to fly the same let alone two different brands.
The Sierra Match King and Game king as example, they try to say the bullets are similar enough to hold the same groups,, I haven't seen it in my experiance with those two in two different guns and calibers.

[Larry L]

When you fire a rifle, the barrel does not stay still, it whips like it's flexible...because it is. If you've ever heard of finding the node for a specific rifle, that refers to the barrel whip and the bullet exiting the barrel at the exact same barrel harmonic or space/time event. It's not the same for every bullet. To demonstrate what I'm trying to relate, here's a Mini14 filmed at different slow motion speeds so you can see the barrel flex. ALL barrels flex, even the big full bull tubes.
http://www.youtube.com/watch?v=AqgPu9gSmVc


Finding a barrels/rifles node means finding a load that makes the barrel flex the same every shot and the bullet exiting the barrel at the exact same barrel position. It's not the same for every weight or design of bullet. What you're experiencing is the barrel of your rifle is twisting or bending in the direction of bullet impact for each type of bullet you're using.

[huntducks]

Reloading 101 they are diffrent bullets they won't group the same, that why they put them little adjustments knobs on your scope.

[Land_Owner]

Larry L is on the right track but there are still more variables.  In which rifle are you shooting these bullets?  Is the barrel free floated?

A tight forearm screw, hard point between the barrel and stock, or muzzle inconsistency can contribute to this.

[Lloyd Smale]

short answer is yes. It is typical