Long Range Hunting Online Magazine

Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Reloading

Reloading Berger Bullets


Temperature sensitivity of US869

LinkBack Thread Tools Display Modes
Unread 11-24-2006, 05:33 AM
Platinum Member
Join Date: Feb 2004
Location: Pennsyltucky
Posts: 2,630
Re: Temperature sensitivity of US869

i only tested one round last year, it chronod the same.but this would be in of the 5 i keep in my pockets and they seem to impact where they should.that's how i deal with the changing temps.
Reply With Quote

Unread 11-24-2006, 03:14 PM
Platinum Member
Join Date: Jan 2003
Location: The rifle range, or archery range or behind the computer in Alaska
Posts: 3,830
Re: Temperature sensitivity of US869

In one very limited test, we shot three loaded with 92 grs at 98 degrees F. then followed up with three of the same which had been put into a cooler and brought down to 60 degrees. The net finding was about 250 fps of velocity loss for the colder ones.

[/ QUOTE ]

This is quite a bit differant from what I found. Granted, I was using a barrel within a stable temp range and these tests were NOT done with a fridged barrel. I dont know if that makes a differance or not.

Here is what I found:

104 grains of US869 under a 180 ACCUBOND. Powder temp around 67 degrees vs. the same except the powder temp was -7 degrees. The differance was right at about 120 FPS. Thats for 74 degrees of differance.

95 grains of H50BMG in the same scenario was about 74 FPS.

For all of you that hate the RL line, the colder one was faster by 33 FPS! Dont ask me why.

There was one other post here that had similar results.

Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.
Reply With Quote
Unread 11-24-2006, 04:45 PM
Platinum Member
Join Date: May 2001
Location: Windham, CT - in Moo-Cow country
Posts: 1,008
Re: Temperature sensitivity of US869

... The approach is not perfect (at 60 deg the air in the pipe will be denser) - denser air would lower the velocity even more (but probably less than 3%). What a great idea - work up a velocity/temp data chart.

[/ QUOTE ]

Big Bore...

You have taken the art of silly to new, all time heights.

If you want to count the angels on the head of a pin, you must first know the size of their shoes, the size of their waist, and the size of their bra...

Air at 59 degrees "F" = 1.2 grams per liter (1000 cc) or 0.0012 grams per cc or 0.0185 grains per cc @59 degrees

At "0" degrees "F" - 0.0209 grains per cc

Volume... 1 cubic centimeter = 0.061 023 744 cubic inch

volume of .308x26" barrel = 0.6166 cubic inches

Therefore the weight of the air in a 30 cal barrel that is 26" long (NOT including the chamber) is 0.001128939819 grains at 59 degrees and 0.0012753968766 grains at "0" degrees, or a whoppin' 0.0001464570576 grain difference in the weight of the air in the barrel from 59 degrees to "0" degrees.

I think (in my humble opinion) that 0.000146 of a grain weight difference in the weight of the air in the barrel will not make a difference in the velocity... since it is about 1/1000th of the weight difference between bullets of the same lot number [img]/ubbthreads/images/graemlins/wink.gif[/img] [img]/ubbthreads/images/graemlins/wink.gif[/img]
Spring has sprung, da' creek has riz, I wonder where dem kitties is? Here, kitty kitty kitty.

LRH member #23

Reply With Quote
Unread 11-26-2006, 09:45 AM
Gold Member
Join Date: Feb 2005
Location: Texas born and raised
Posts: 752
Re: Temperature sensitivity of US869


When we tried the temp check, the ambient was pushing close to 98 and we had 100% humidity. We had been load checking a few different powder charges and figured that since we had the drink cooler with us we would try the test. We stuck three rounds in the cooler, for about 30 minutes. After we put them in the cooler, we put three consecutive rounds of the ambient temp loads through the chrono. After letting the barrel cool and the three in the coller reach the ambient temp of the cooler, we fired them through as well.

Granted this wasn't too awefully controlled, but it was something that has repeated since the weather has cooled somewhat down this way.

Bear in mind, down here where we are shooting it is generally in the 60% humidity levels and we are at most only 170ft above sea level. Our max loads with the 869 or the 872 generally run somewhere in the range of 5 - 9 grs below what most can get, before we start getting pressure signs. Yes we can run the loads up to about 98grs with the 169.5 but then the cases only last about three loads before being trash.

Just thought I would throw in what we have found.
Mike / Tx

My Photo's

"Heck why would I lie, most folks don't believe the truth when I tell them"
Reply With Quote
Unread 09-23-2014, 10:07 PM
Official LRH Sponsor
Join Date: Mar 2007
Location: Montana
Posts: 2,929
Re: Temperature sensitivity of US869

I am pulling this up from the deep catacombs to see if anyone has anything to add to this thread. Would like to hear experience with US869, WC872, and WC860. Experience with over bore top pressure loads in different temps would be helpful. I have been experiencing some pretty big pressure increases with 869 and top loads with only 20 deg temp increase.

Hammer Bullets
Advanced Technology
Simply Better

To hunt... or not to hunt...? What a stupid question.
Reply With Quote


Thread Tools
Display Modes

Similar Threads for: Temperature sensitivity of US869
Thread Thread Starter Forum Replies Last Post
Temperature Sensitivity Jim Hundley Reloading 5 10-25-2010 07:08 AM
Powder Temperature Sensitivity vintec Reloading 16 01-31-2009 02:04 AM
Temperature Sensitivity/Insensitivity 300winnie Reloading 6 06-13-2006 02:10 PM
Temperature sensitivity nelson Rifles, Bullets, Barrels & Ballistics 0 02-05-2006 07:33 PM
Powder sensitivity to temperature RBrowning Rifles, Bullets, Barrels & Ballistics 7 01-23-2003 11:43 PM

All times are GMT -5. The time now is 06:44 AM.

All content ©2010-2015 Long Range Hunting, LLC