However, I do believe that these programs provide a valuable service in both unknown conditions when you need some guidance , and in known conditions for doing what-if scenarios, such as changing velocity by 100 fps and finding the difference in point of impact.
And there in lies the problem. You CAN'T know if the next shot you make will have a different velocity or not (actually, you shouldn't need to but I will get to that in a sec).
I fully agree having spent hours mucking about with JBM online, it is a great way to show you what changes in this and that should/could have on your shot. I have compared so many variables, you wonder what normal atmospheric conditions are
Now with the addition of Litz data, we can have a much better comparison of bullet performance at distance and YES, his data does work pretty darn well.
So as a learning tool, superb and highly recommended.
As a field tool, unless you plan on shooting in grossly different environments AND extremely long distances (I shoot out beyond 1 mile), it is really not much better then your printed drop chart.
And whatever program you decide to use, make sure it allows the chart to adjust for real world inputed data. Something as simple as a scope click value can throw everything off.
Ok back to how to reduce the headache of equipment changes over big temp and condition changes. Full details on my website and longrangehunting.com but it boils down to powder and load tuning.
I use Hodgdon Extreme and it is one of the most temp and ambient condition stable powders I am aware of. However, I try and keep my operating temp range to 20C - this you need to test with your rifle under real world conditions. Some will be wider, some smaller but you need to know.
Within this operating window, I find my loads to stay stable and my drop chart to work. So I can hunt from 20C to 0C without worry that my velocity is going to change enough that my drop chart varies enough to miss my intended target at distance.
I definitely will test and tweak my loads as close to my operating temp as possible. So yes, if you hunt in -15C, test in -15C.
If you are using a rifle/ammo/scope combo that varies based on ambient conditions, you are courting with disaster. Properly set up LR rigs shouldn't.
All the handheld gear in the world cannot predict what your stock, scope, barrel and ammo may do under changing ambient conditions
Now I am not saying that you are accurate to the 1/4" at 1000yds, BUT you can be accurate to min of big game if your prep work and shooting skills are dialed in.
I would use the portable programs in a heartbeat if it would help me in my shooting or hunting endeavors but I find that proper gear and prep works just fine.
And the various areas I shoot are similar enough in climate that it really doesn't matter.
That twitchy wind bouncing off that next hillside will do me in way before a falling barometer does.
Jerry
PS anyone up to doing that sunlight test?