Shooter Program Question

[BrentM]

In the SHOOTER program there is a switch that enables and disables powder temperature. Selecting this option makes a fairly significant change down range on MOA adjustments. Basically it is adjusting velocity for a given temperature that outside the temperature used to zero your rifle.

With the temp stable powders from Hodgon is this part of the program necessary or should it be ignored? I have not yet had a chance to put the numbers to work in real life.

 

[Broz]

Just leave them blank if you do not have all the data yet (MV variation & powder temp). Then the program will work off the inputted data you have. It will work fine that way. But I do feel as you go out past 1000 yards this data could become more important if you are dealing with large swings in ambient temperature.

Then comes the question of what to do about ammo temperature. Is it in a warm pocket, cold pack, just out of the truck or is the ammo also at ambient temperature?

I am doing some testing on this and don't have all the data yet. But I feel the most consistent method will be to keep ammo at ambient temps and not in direct sun.

Jeff

 

[BrentM]

For example when I shot the new loads last weekend it was 47 degrees, 4125 feet, and the powder was in the truck as we reloaded in the field. The temp inside the truck was 60. I took the load to the rifle and popped it through the chrono. So zero would be 4125 and 60 degree's which equaled a FPS of 2975.

Shooter know's this. So then if I am packing a mag full of cartridges and the outside temp is 30 we could easily assume the powder is going to be quite close to that as well. The adjusted velocity is significant. 240 fps difference. Seems way off to me with extreme powders.

 

[Broz]

. So then if I am packing a mag full of cartridges and the outside temp is 30 we could easily assume the powder is going to be quite close to that as well. The adjusted velocity is significant. 240 fps difference. Seems way off to me with extreme powders.

I get no where close to the results you do. Never have I seen 240 fps even with much larger ambient temp swings.

I suspect a couple things. Chronograph to close to muzzle blast, needs to be at least 18 ft. Was this a "shooting Chrony"?

 

[Broz]

Just looked and my last test was with my 300 win at 1007 yards. Comparing shots fired at 55 degrees and then again at 20 degrees there was less than 20 fps variation in MV and this was verified by sub 1/2 moa groups on the target.

Jeff

 

[BrentM]

As I said the Shooter program makes this velocity change. I am thinking this is not a useful part of the program. I can not imagine there being that much difference.

 

[Broz]

As I said the Shooter program makes this velocity change. I am thinking this is not a useful part of the program. I can not imagine there being that much difference.

Sorry I mis-understood. The user inputs the data, so I think you need to look closer. I say you have inputted the wrong data in the "MV variation" that is where you input the "fps per degree" "fps/*"

Jeff

 

[BrentM]

I input 8.00. I think I see your point. MV in that calculation is FPS per Degree of temp change. I was thinking it was FPS spread. No wonder it was such a mess.

What do you use for a number?

 

[Broz]

I input 8.00. I think I see your point. MV in that calculation is FPS per Degree of temp change. I was thinking it was FPS spread. No wonder it was such a mess.

What do you use for a number?

I am not using it yet as I am still gathering data to average. But lets say you have a drop of 20 fps when the ambient temp drops 40 degrees. That is a drop of 1/2 fps per degree. So the MV Variation would be .5 and the powder temp would be the day of zero sight in, and muzzle velocity of that day at that temp. Like I said I am not using it yet, but that is the way I understand it. Someone correct me if I am wrong here.

Jeff

 

[BrentM]

I agree now that I understand what you were saying. I have to DOPE this rifle anyway and will see what I can gather for info as well. For a month we had temps in the 0 to 10 range and now the temps are 20-40.