Post by sevenfan on Apr 22, 2023 10:50:14 GMT -5
I've had the program for a couple years and only now starting to really learn it. I posted elsewhere about barrel time and nodes, something I'd read about years ago but never really understood until I happened upon the OBT calculator.
I also know the powder values are not as accurate as a load manual, the data never matches when I use the exact info from a manual and plug those values into QL.
As mentioned in my reply in the Berger VLD topic, I've been working with my brother's 7RM and planned to load the 168gr Hunter VLDs because I could not find any 160gr Partitions a year ago. By the time he brought the rifle I had located 160 Partitions.
I've played with QL quite a bit the past few weeks to get good start data fully aware the Ba factor would most likely be incorrect - it sure was. Rather than err on the safe side, QL Ba factor data was actually on the high side of safe.
Using H1000 with the default Ba factor, QL showed 67.8gr & 70.5gr H1000 to be dead on the low and high nodes and well below max pressures at 48kpsi & 55kpsi respectively. I felt that was a big enough safety margin to proceed even if the Ba factor was wrong.
I started with 3rds originally loaded in 1992 using 61gr IMR4831 - they averaged 2809fps in a clean barrel.
QL predicted the low node to be 2820fps with 67.8gr H1000, 3 shots averaged 2937fps - 128fps faster than predicted.
The high node was predicted at 70.5gr and 2948fps, they averaged 3014fps with some lift resistance which I expected with the new Norma brass.
After correcting the Ba factor to match actual chrono data, the low node charge weight dropped from 67.8 to 65.4gr/2826fps/1.308ms (node is 1.309ms). Plan to load 6ea @ 65.4 and see how they shoot.