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Do you enable Powder Temperature using Shooter?

 
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  #1  
Old 12-04-2013, 01:16 PM
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Join Date: Oct 2013
Location: Texas
Posts: 99
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!
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  #2  
Old 12-04-2013, 01:36 PM
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Join Date: Jan 2013
Location: Meridian, Idaho
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Re: Do you enable Powder Temperature using Shooter?

Are you Editing the powder temp in the Ammo field? If so, this is not what you want to do IMO. You set the zero up for the conditions of the day and leave it alone, UNLESS, you rezero in different conditions.

You adjust temp on the main page for the current conditions. Generally the differences in temp do not affect the FPS that much until you get into wide swings. For example 10 to 90 F. I have shot those conditions actually. LOL.

For me: I set the temp of the powder close to the conditions to which I shot for the zero. For example 50F. I set the atmosphere of the conditions I zero etc. This is the constant. Then I set all the parameters in which I am shooting, which is now the variable. So constant is my zero and variable is my shooting conditions. Shooter has worked extremely well for me out to 1660 yards in wide variety of terrain and conditions. Going for the mile soon. ha ha
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Old 12-04-2013, 01:49 PM
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Join Date: Oct 2013
Location: Texas
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Re: Do you enable Powder Temperature using Shooter?

No, I am not messing with the initial inputs or editing the data. This is just entering in the current data in order to come up with a firing solution. It is just giving me huge swings in MV when the powder temp is set to same as outside temp.
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Old 12-04-2013, 03:06 PM
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Join Date: Jan 2013
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Re: Do you enable Powder Temperature using Shooter?

OK, sorry I can't help you then. I don't have that feature on my Shooter program. It is on a iPod and I got it in February. Most be something new they added or for the iPhone.
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Old 12-04-2013, 03:38 PM
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Join Date: Mar 2008
Location: SD
Posts: 256
Re: Do you enable Powder Temperature using Shooter?

Under the Edit Ammunition page do you have MV Variation and Powder Temp?

I put in the Muzzle Velocity and Powder Temp when I zero my rifle. Powder Temp is the temperature outside (your ammo needs to be set out so the powder becomes the same temp as outside)

Now shoot on a completely different temperature day. Have it be a significant temperature difference. I sometimes leave my ammo outside overnight and check in cooler morning temps.

Get the second shooting day Muzzle Velocity and Powder Temp. Don't put this in the Muzzle Velocity and Powder Temp, leave them alone.

Now use both days of MV and Powder Temp to calculate the difference in fps/degree change. Put this in the MV Variation.


Example...

So on day 1 3000 fps/100 degrees F
So on day 2 2970 fps/70 degrees F

You would have a 1 fps/degrees F change - put that in the MV Variation.

I believe it is the same in Applied Ballistics and Shooter.


If I am wrong someone please correct this.
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Old 12-04-2013, 04:03 PM
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Join Date: Oct 2013
Location: Texas
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Re: Do you enable Powder Temperature using Shooter?

Hey thanks drbill, that helps. I did not know what MV variation was, thought it had something to do with ES or SD. I have changed it to 1 fps for time being until I can get some hot and cold MV's.
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Old 12-04-2013, 04:41 PM
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Re: Do you enable Powder Temperature using Shooter?

MV is FPS/per degree. If that is what you are doing then it likely is causing your issue. As noted by the last poster if you use 1FPS/degree a 20 degree outside temp change will give you a 20 FPS variance. That is actually quite a lot.

You will need to chono or dope this to find out the real affect. Most people input something like .25 to .5 for fps/degree. Gunwerks has a video that shows the difference in sensitive vs extreme powder variances in FPS. I think the did 32F and 90F or something like that. I use extreme powders and have virtually no variance from 10f to 90f.
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