Do you enable Powder Temperature using Shooter?
I was out testing some loads this last weekend shooting at 700 yards (farthest I have readily available at our ranch in East Texas). I just downloaded Shooter last Friday and have been setting it up and learning how to use it. When I chrono'ed my 7RM it was 59 degree's and 41% humidity. As I was playing with Shooter and trying to learn how to use it I noticed where it said "Enable Powder Temperature" and went ahead and checked the box to enable.
I had some serious issues because when I went to shoot at 705 yards I input a temp of 63 degree's which was accurate, and since the powder temp adjustment was enabled it automatically changed my powder temp to 63. So it gave me a solution, I dialed in 13.4 MOA, and was around 8" low, or roughly 1 MOA. So I adjusted the scope 1 MOA up, and I was in business. At this point I had not played with the Shooter app powder temps so I was kind of at a loss as to why I had shot 1 MOA low. I was later playing with it and set the powder temp to 59 degree's... a change of 4 degree's in temp, and it told me to dial 14.6 MOA, right where I ended up.
Sooo, I started playing with the powder temps.
Wow, the results that came out were shocking to say the least. I entered a MV of 2800 fps to experiment with at the aforementioned 59 degree, 41% humidity and altitude of 450' above sea level. I do not have a Kestrel at this time (trying to decide whether to keep my Leica CRF1200 and buy Kestrel, or sell the Leica and buy Gunwerks LR2, kind of leaning towards LR2 as I have nowhere to shoot over 1200 yards around here) so I did not know the actual Baro Pressure. Just left it as default.
Anyway, when I put in an outside air temp of 40 degree's and let it default the powder temp to 40, it came up with an adjusted MV of 2439.57 fps...! I then tried the air/powder temp at 70 degree's and it came up with 3008.67 fps...!! So to take outside air temp out of the equation I set the air temp at 59 and just changed the powder temp between 40 and 70 degree's. Same results.
So this thing is telling me that for a 30 degree change in powder temp that I am going to get a 560fps change in MV? Now, I know that this is not accurate, but am I inputting something wrong to get these results? When I hunt I do normally have rounds in the rifle instead of taking them out of my pocket and loading when I need them so I do need to learn the differences the outside temp makes on my MV, but I know that it is nowhere near what the program is spitting out.
So am I doing something wrong or do I just leave the Powder Temp alone on Shooter? You should see the solutions it came up with at those two very different MV's!
Army Field Artillery