Powder and temperature.

toolguy2006 · January 15, 2012, 03:46 PM

I have been using IMR-4895 for some time now, and I was wondering how much temperature affects this stuff. For instance, every time that I head to the range on a day the is colder than the day the rounds were loaded, I swear that the groups open up by quite a bit. I am talking temperature swings of 20 degrees or so. For instance, I just came home from the range, and it was a steady 30 degrees today, but outside temp was up in the mid fifties a couple weeks ago when I loaded the ammo. It doesn't really make sense to me that rifle powder could really be this sensitive, especially at a hundred yards from a stock deer rifle. Any opinions?

3kgt2nv · January 15, 2012, 03:51 PM

I havent seen the same when using the powder but i have noticed a trend that when its super cold like that I tend to overgrip the rifle because my hands are colder and it changes my hold on the rifle.

Hog Buster · January 15, 2012, 08:11 PM

A while back this came up and if I remember correctly Hogdon said that H4895 had a 20 fps velocity difference between 0 degrees and 125 degrees. They also stated that IMR 4895 had a spread of 160 fps at the same temperatures. True? Who really knows? Being that both have been used as a military rifle powder I would think that temperature variations were taken into consideration when choosing it. I’ve used both for years in most of my rifles and have seen no difference caused by the moderate temperatures I experience.

toolguy2006 · January 16, 2012, 02:49 PM

Well, like I said, it didn't really make sense that rifle powder would change that much. Guess I have to admit that I just wasn't shooting that well and quite blaming the powder.

bbrownie · January 16, 2012, 04:27 PM

Alliant Reloader 15 powder was developed for the U.S. Military and is not effected by extreme temperature change.

rclark · January 16, 2012, 05:35 PM

Quote:

Guess I have to admit that I just wasn't shooting that well and quite blaming the powder.

. I know my groups open up when shooting in <20F weather compared to in the >30F! Trigger just doesn't 'feel' the same when fingers are 'cold'.

amathis · January 16, 2012, 05:58 PM

Granted I could be dreaming but my pet hunting load in 300WM goes from sub 1in when it is 30 degrees to around 1.5 when it is 70 out. Ticks me off to no end. I lost a turkey shoot because of it. . . . . .

I'm using Win Supreme 780 in that load for those wondering.

Slamfire · January 16, 2012, 06:59 PM

That is a difficult question. Wish I had a better data set with wider temperature spreads and more data points. So in a sense, this is a worthless post.

There is the problem of calibration. When I set up my chronograph I try to align as best I can and shoot known ammunition over it, to ensure I am in the ball park, but there is alignment error and I cannot quantify that.

The chronograph does not work well in 40 F weather because the battery voltage drops and you get nonsense velocities.

The White Box match was loaded with IMR 4895.

Code:


Ruger M77 MKII 308	26 " Barrel 1:10 twist

174 FMJBT LC79 Match M118 White Box 		
18 May 2008 T =  71 °F				
					
Ave Vel =	2590				
Std Dev =	11				
ES =	35				
High =	2609				
Low =	2574				
N =	9				
	excellent				
					
					
	
					
174 FMJBT LC79 Match M118 White Box 		
18 Dec 2010 T =  40 °F				
					
Ave Vel =	2546			 	
Std Dev =	17				
ES =	41				
High =	2572				
Low =	2531				
N =	5				
					



174 FMJBT 42.0 grs TALON Surplus 4895 CAVIM 90 CCI#34 		
					
14 Nov 2011 T =  68 °F				
					
Ave Vel =	2500				
Std Dev =	20				
ES =	39	 			
High =	2521			 	
Low =	2482	 		 	
N =	3				
					
					
174 FMJBT 42.0 grs TALON Surplus 4895 CAVIM 90 CCI#34 		
					
29 Dec 2011 T =  44 °F				
					
Ave Vel =	2451				
Std Dev =	24				
ES =	62	 			
High =	2480				
Low =	2418	 			
N =	5

January 15, 2012, 03:46 PM	#1
toolguy2006 Senior Member Join Date: December 28, 2010 Location: Western Washington State Posts: 144	Powder and temperature. I have been using IMR-4895 for some time now, and I was wondering how much temperature affects this stuff. For instance, every time that I head to the range on a day the is colder than the day the rounds were loaded, I swear that the groups open up by quite a bit. I am talking temperature swings of 20 degrees or so. For instance, I just came home from the range, and it was a steady 30 degrees today, but outside temp was up in the mid fifties a couple weeks ago when I loaded the ammo. It doesn't really make sense to me that rifle powder could really be this sensitive, especially at a hundred yards from a stock deer rifle. Any opinions?

January 16, 2012, 04:27 PM	#5
bbrownie Junior Member Join Date: July 21, 2010 Location: Southern Ontario Posts: 6	temperature change Alliant Reloader 15 powder was developed for the U.S. Military and is not effected by extreme temperature change. Last edited by bbrownie; January 16, 2012 at 04:27 PM. Reason: spelling

January 16, 2012, 06:59 PM	#8
Slamfire Senior Member Join Date: May 27, 2007 Posts: 5,261	That is a difficult question. Wish I had a better data set with wider temperature spreads and more data points. So in a sense, this is a worthless post. There is the problem of calibration. When I set up my chronograph I try to align as best I can and shoot known ammunition over it, to ensure I am in the ball park, but there is alignment error and I cannot quantify that. The chronograph does not work well in 40 F weather because the battery voltage drops and you get nonsense velocities. The White Box match was loaded with IMR 4895. Code: Ruger M77 MKII 308 26 " Barrel 1:10 twist 174 FMJBT LC79 Match M118 White Box 18 May 2008 T = 71 °F Ave Vel = 2590 Std Dev = 11 ES = 35 High = 2609 Low = 2574 N = 9 excellent 174 FMJBT LC79 Match M118 White Box 18 Dec 2010 T = 40 °F Ave Vel = 2546 Std Dev = 17 ES = 41 High = 2572 Low = 2531 N = 5 174 FMJBT 42.0 grs TALON Surplus 4895 CAVIM 90 CCI#34 14 Nov 2011 T = 68 °F Ave Vel = 2500 Std Dev = 20 ES = 39 High = 2521 Low = 2482 N = 3 174 FMJBT 42.0 grs TALON Surplus 4895 CAVIM 90 CCI#34 29 Dec 2011 T = 44 °F Ave Vel = 2451 Std Dev = 24 ES = 62 High = 2480 Low = 2418 N = 5 __________________ If I'm not shooting, I'm reloading.

January 15, 2012, 03:51 PM	#2
3kgt2nv Senior Member Join Date: January 7, 2012 Location: hudson valley NY Posts: 517	I havent seen the same when using the powder but i have noticed a trend that when its super cold like that I tend to overgrip the rifle because my hands are colder and it changes my hold on the rifle.

January 15, 2012, 08:11 PM	#3
Hog Buster Senior Member Join Date: October 26, 2009 Location: Pointe Coupee, Louisana Posts: 772	A while back this came up and if I remember correctly Hogdon said that H4895 had a 20 fps velocity difference between 0 degrees and 125 degrees. They also stated that IMR 4895 had a spread of 160 fps at the same temperatures. True? Who really knows? Being that both have been used as a military rifle powder I would think that temperature variations were taken into consideration when choosing it. I’ve used both for years in most of my rifles and have seen no difference caused by the moderate temperatures I experience. __________________ Those who beat their guns into plows, will plow for those who don't.-Thomas Jefferson

January 16, 2012, 02:49 PM	#4
toolguy2006 Senior Member Join Date: December 28, 2010 Location: Western Washington State Posts: 144	Well, like I said, it didn't really make sense that rifle powder would change that much. Guess I have to admit that I just wasn't shooting that well and quite blaming the powder.

January 16, 2012, 05:58 PM	#7
amathis Senior Member Join Date: March 20, 2009 Location: Champlain Valley, Vermont Posts: 161	Granted I could be dreaming but my pet hunting load in 300WM goes from sub 1in when it is 30 degrees to around 1.5 when it is 70 out. Ticks me off to no end. I lost a turkey shoot because of it. . . . . . I'm using Win Supreme 780 in that load for those wondering.