I was perusing the Missouri Bullet Co. website, and came upon this is the "technical" section. They claim that there is a formula to calculate the correct BHN for a given load, if you know the CUP for that load. For those interested, here is the link -
http://www.missouribullet.com/technical.php
What it says, is that the formula for the correct BHN is "Optimum BHN = CUPS/ (1492 x .90)",
which is a longer way of saying
BHN = CUPS/1279.8
There is a published load on Hodgdons site, 200gr LRNFP with7.8gr Universal is 15,400 CUPS (and 1045fps from that barrel)
So, according to them, my load of 7.5gr Universal under a 200gr LRNFP needs a BHN of just under 12. I am shooting that load with a boolit that tests at that BHN, and getting a very small amount of lead at the forcing cone, but I think that's a forcing cone issue, not a load/lube/boolit issue. That will be a completely different thread.
Anyway, there is no explanation on the site about what that number (1422 x .90) represents. For all I know, they picked it off a price tag on a used fleece parka at the local resale shop.
My question is basically ..... uh.... really ?
- anybody familiar with this formula ? any idea from where it came ?
Anybody ever use it ?
What the heck does that number (1422 x .90) represent ? ?
Comments ?