Temp differences and MV - Page 2

cw308 · January 13, 2019, 04:28 PM

My season for shooting is in the warmer months 50 degrees on up , I'm only shooting 200 yards my rounds vary within 2" in drop only from 50 on up . Cold being 50 the lowest group as it reaches the 70's shooting at a 1" square I don't adjust just horizontal anymore just hold at bottom middle and top of the 1" square target as temps fluctuate. Using IMR 4064 mild load 168 gr Sierra MK

jimbob86 · December 4, 2019, 09:14 PM

Someone above mentioned that some powders vary in burn rate more than others ..... my experience is that slowish ball powders, like H414, are harder to ignite evenly in cold weather ....... SD as measured on the chronograph grows and MV drops ....... substituting a magnum primer for the standard primer solved the issue for me at the time..... though I never did try that load in the summer heat ...... probably not a good idea.

January 13, 2019, 04:28 PM	#26
cw308 Senior Member Join Date: September 2, 2010 Location: Plainview , Long Island NY Posts: 3,863	My season for shooting is in the warmer months 50 degrees on up , I'm only shooting 200 yards my rounds vary within 2" in drop only from 50 on up . Cold being 50 the lowest group as it reaches the 70's shooting at a 1" square I don't adjust just horizontal anymore just hold at bottom middle and top of the 1" square target as temps fluctuate. Using IMR 4064 mild load 168 gr Sierra MK

December 4, 2019, 09:14 PM	#27
jimbob86 Junior member Join Date: October 4, 2007 Location: All the way to NEBRASKA Posts: 8,722	Someone above mentioned that some powders vary in burn rate more than others ..... my experience is that slowish ball powders, like H414, are harder to ignite evenly in cold weather ....... SD as measured on the chronograph grows and MV drops ....... substituting a magnum primer for the standard primer solved the issue for me at the time..... though I never did try that load in the summer heat ...... probably not a good idea.