Quote Originally Posted by dverna View Post
This is most interesting as it is unexpected. Ballistically, a 100 fps variation cannot effect POI by 2" at 50 meters. Trying to determine why this is happening is making me scratch my head. BTW, I am not doubting your information...only attempting to understand. You have done enough testing to confirm the phenomenon in this particular rifle, and this determination would not have been possible without chronograph data. BTW, this is the first time I have seen a chronograph make a significant contribution to developing a load for practical purposes.

Do you think barrel/action harmonics in a lever action (or at least your 336) have a greater effect than with other platforms? Thus a 100 fps difference has a more pronounced affect than a simple math calculation of POI change due to velocity change?

But your post is why I made the challenge here....to learn. What I read about using chronographs is always about "precision rifle shooting" at ranges most ethical hunters would pass on.

Also, I want to thank the others who are responding. Your information tends to confirm my understanding and opinions.

I should have added in the first post that I do not go "off the reservation". I use powders that are published for the caliber and bullet weight (or close to it). My goal is to find the most accurate load at close to peak performance. If max charge is 45 gr and my accurate load is at 43 gr. I stop working on the load. "Losing" 100-125 fps by being under maximum is not important to me.
A little late, something to consider. The dwell time in the barrel plays a big part in POI. I found massive differences in POI between .44 Special velocities and Ruger/Contender only loads with my 14” Super .44 Contender. Granted, the difference was way more than 100 fps but I think the example is valid. Off of a bench and rest the 1600 fps loads shot more than 18” lower than the 850 fps loads at 50 yards.

I do abide by the philosophy of matching velocities with new batches of a powder.