Do you think the 1.349 ms value is really different from 1.333 ms in terms of being "in the node"? Node 4 for a 26" barrel is ~1.191 ms and Node 6 is ~ 1.415 ms. 1.349 ms is a lot closer to the Node 5 1.333 ms value in the table than it is to either of the adjacent values. My point is simply that when you look at the values in the OBT table, you find the next OBTs on either side of the 1.333 ms value are much farther away in terms of barrel time (as well as pressure and velocity) than your predicted load barrel time of 1.349 ms. Your QL inputs, how you calibrated QL for your specific setup, and the conditions all have a significant influence on the predicted barrel time readout. 1.349 ms is close enough to the Node 5 table value that the difference could easily be in the inputs or calibration method you used, or possibly even the specific atmospheric conditions.
Did you adjust the Ba for your specific Lot of powder so that predicted and actually velocity match exactly for a given charge weight? How did you determine your case volume? Did you adjust the temperature to match the ambient temperature when you were actually testing these rounds? Have you adjusted the seating depth for this load so as to optimally tune group size? What did the velocity ES/SD values for these two loads look like? Did you use the actual case trim length and bullet OAL? Have you actually measured the length of your barrel from muzzle to boldface? It appears from your file output that you have done some of these things, but you apparently have not yet "calibrated" the Ba for IMR4064 to your specific setup (i.e. set the correct temp, then adjust the Ba until predicted and actual velocities match exactly for a given charge weight). Failure to do all of these things and use the best possible input data for the program can result in predictions that are less precise.
As a result, there is a lot more to tuning a load using OBT nodes than simply trying to approximate some optimized barrel time from the table by adjusting charge weight. You still need to "tune" the charge weight within that window for your specific setup, and further will likely need to optimize seating depth before you have an actual finalized load. With the very best load-specifc QL inputs I can generate, my final optimized load values typically fall just a tick slower than the OBT value printed in the table. For example, I have several loads in 30" barreled rifles that were targeted on Node 4 (1.3684 ms). My final QL barrel times for those loads have typically fallen in the range of ~1.371 to ~1.375 ms, sometimes (rarely) even as slow as 1.380 ms. After calibration, I use QL predictions to get me in relatively close proximity to an OBT Node, then tune it in specifically for my setup, just like I would do using any other approach.
My guess is that your 1.349 ms is running at or very close to Node 5 for your setup. It is certainly much closer to the Node 5 barrel time than it is to those on either side. I would also guess that if you continue development and refine that load to its optimal point, then use the the best measurements, etc., that you have as QL inputs for the finalized version of the load, it will come out a lot closer to 1.333 ms.
Shot two different loads today. I based one off the best OBT (1.333 for a 26") which was the QL data you see pictured here below.
