Thread: Load Data Conundrums.

Greetings All, @Micky Duck you are correct that the grooves reduce engraving resistance but they are still harder and longer than cup and core projectiles due to the solid copper construction. They also need to be seated much further from the rifling as detailed by Barnes in their load data which reduces peak pressure some.
We had a thunderstorm last night and it was wet out this morning. Did not feel much like outside work so I did a little research. I was looking for Ken Waters second Pet Load report which I found and additionally a Propellant Profiles report on H1000. This was done by Sam Fadala in 1989 just after H1000 was released. I was interested to see how this differed from later data currently published by Hodgdon. It certainly did. A single load was listed for the 160/162 grain projectiles with the start load being higher than the max load shown in current data, even for the hotter 162 grain Hornady BTSP projectile. Current max pressure for the 7mm Rem mag is 52,000 CUP or 61,000 PSI and this data went to 55,500 CUP. Crikey!
Since this data was produced two things have happened. First the powder industry has moved to electronic measurement of pressure (PSI). This is more sensitive and accurate and showed wider pressure swings, with some cartridges, than expected. Additionally H1000 (AR2217) production was moved to Australia from Scotland around 2,000. One of the thing I have found helps understanding different load data sets is to plot them on a graph. This was done for the 160/ 162 grain data plus the 162 grain Hornady BTSP and 160 grain Nosler Partition data. Extending the line for the 162 grain BTSP projectile showed that it was close to the hot 160-162 data. The latter data gave a little more velocity for a little less pressure at the same load level.
So here is the conundrum. Would I push on a little from the current data toward the older data. The .300 Win Mag has a max pressure of 64,000 PSI and my little 7mm SAUM max is 65,000 PSI. Frankly I don't know. No doubt there are those that do but likely not me.
Regards Grandpamac.