Does anyone use LFD and trust it's calculations? I purchased it a few years ago and find it to be completely worthless. Either I am doing something wrong or this software is BO.
For example:
300WSM, 180gr Sierra SPBT, 24in barrel, AA 4350 powder.
LFD calculates
58.7gr Max
2697fps
45307 CUP
AA Data
Start 60.3gr 2722fps
Max 67gr 3024fps
61,300PSI
That's over 8gr difference. LFD lists Max below the safe starting point according to AA. This discrepancy occurs with all powder and bullet combos in the 300WSM and other cartridges as well.
The data seems to match pretty well for about 60 grains. The only issue there is what LFD says is maximum. Note that one uses CUP while the other one uses psi. That could be a large chunk of the apparent difference.
Furthermore, when I run it, it does NOT show 58.7 grains as MAX. It shows charges ranging from 51.6 through 68.8 grains, with 65.3 and 68.8 being labeled as HIGH Press. It shows 59.1 as an OPTIMAL load, not MAX. That loads gives 2696 fps at 45,400 CUP.
The 95% case capacity load shown is 65.3 grains, for 2979 fps and 54,961 CUP. Which is darn near identical to what the AA manual says.
Thanks Rocky, I guess I just don't get it. When the program says, OK,OK,OK,OK, then "High Pressure" I take that to mean High or excess pressure. With this program there are only two kinds of pressure, OK and High. In my mind when it changes from OK to High, I would call that Max.
Mine shows charges ranging from 51.6 to 68.8 grains with 51.6, 55, 58.8 listed as OK and 61.9, 65.3, 68.8 listed as High pressure. To me that means that 58.8 is OK and 61.9 is not OK. With this program I certainly wouldn't have concluded that 65.3 was OK.
And why does it list all cartridges in CUP?
Either our versions are calculating differently, are using slightly different values for input, have slightly different pressure limits, or one of us is changing the cartridge parameters slightly.
Mine gives almost identical charges, but doesn't show HIGH PRESS until the 65.3 load.
I'd have to ask Wayne why he sticks with CUP, but I'm going to guess that it's related to the original algorithms coming from Powley, and those are the units he worked with. (CUP = Calculated Under Powley, LOL?) If you change to psi, the calculations would all have to be re-done.