Troutslayer
Well-Known Member
Is calculating MV more like a best guess without a chronograph or can I get pretty close knowing barrel length, powder, bullet weight? What kind of formula/freeware do I use?
Using the load info will not get you accurate enough for much, as different rifles behave much differently.
If you have a drop chart and all the environmental conditions, you can work backward and get a fair guess with one of the ballistic programs.
For example my 7mm Rem Mag, shooting 160gr Accubonds is sighted in at 200yds, the sight height is 1.5" and I have to crank 14.75 moa up to hit at 800yds when at 7480' elevation. By playing around with the program I can see that I am around 3000fps.
My chrono tells me That I average 3015.
Your best bet is to spend a couple hundred $$'s on a good chrono and use it. It will save it's cost in ammo over the next few years.
HTH,
AJ