Raven’s comments are valid ones. It’s what shows on the paper that counts.
With regard to tune, the simulation programs using SD’s do not reveal the full picture in many cases as to what the muzzle is doing.
In this scenario, it is that third point of inertia I have explained before IMO which is responsible for the muzzle chatter. The chatter area will affect all tune types on a micro level compared to fundamental barrel swings. Whether they are the OCW tune which tries to tune out muzzle distortion; a harmonic nodal tune where vibrations are in balance; or a compensation tune where there is an intersection of high and low velocity shots at a specific distance.
Tests need to be repeated at distance in order to clarify the following e.g. a) was the rifle compensating at the short distance. b) Mid point trajectories are a good place to view vertical dispersion in relation to the trajectory characteristic of three distinct tune types mentioned above. c) Was the SD representative of a decent sample. d) How relevant is the SD to the style of tune?
My approach, and I only use a chrono for plotting initial charge tests to trace the fall of low and high velocities on the paper to identify the barrel tune type then to find the best tune on paper for that barrel’s natural condition, then add a tuner to the system to take it through its paces to see what tune type does with the tuner on and whether I can improve things. There are many ways to skin a cat. You could find the load with the lowest SD and use a tuner to change group shape. This usually applies to barrels showing muzzle distortion when returning waves interfere with bullet exit. You can have a low SD, but if the muzzle is being distorted the groups are not as tight as they could be. Bit like a poor crown. Other advanced methods can determine a suitable harmonic length for the barrel, extra muzzle weight to take out torque factors which mainly affect bag handling. Just a perspective.
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