Originally Posted by MontanaRifleman
I have to disagree about using velocity and a chrony as an absolute pressure indicator for all the reasons I list in my previous post. I'll also add this.
Off the shelf chronys are not completely reliable instruments. I have seen reading up to 70 fps difference from 2 chronys placed back to back. I have seen the same chrony chrono the same load and avg 50 fps faster in the evening when in shade than earlier that afternoon in the sun in about the same temp. Changes in outside temps will affect pressure and velocity even if the instrument was 100% reliable. Overall, my chrony's give me fairly good info but they have a lot of quirks.
I just did an online check of Hodgdon and Nosler reloadong data for the 7 RM and 160 Nosler bullets. Hodgdon lists a max charge of IMR 4350 @ 59.5 gr with an MV of 2856 fps. Nosler lists 60 gr with an MV of 2998. How do you account for that? That is 142 fps difference in published max velocity using the same powder and bullet.
I have seen 50 fps difference between using RP and WW brass with the same load in my 25-06.
I can get 3200 fps plus pushing 180 E-Tips with RL17 out of my Sako 300 WSM
and have been accused of the same thing Rich is being accused of several times in this forum and another. I use the very same pressure signs to determine that max load as I do with H4350 pushing the same bullet out of the same rifle With a max load velocity of about 3000 fps which is very close to published and factory for 180 bullets. Interesting enough is the fact that RL17 could only push 168 TTSX's about 3150 fps out of the same rifle using the same pressure indicators. That rifle happened to like RL17 pushing 180 E-Tips through it. Part of the reason is it was long throated and I loaded the E-Tips to just off the lands which increased case capacity. I could tell a very similar story with my 25-06.
Just wayyyy too many variables and inconsistencies to say for certain that a published load or velocity is the determiner.
I've derailed this thread enough already to go through and answer this one.
If you really want me to answer this post it somewhere or feel free to PM me.